U.S. patent number 10,463,391 [Application Number 16/151,471] was granted by the patent office on 2019-11-05 for magnetic ferrocenyl-functionalized nanoparticle.
This patent grant is currently assigned to King Fahd University of Petroleum and Minerals. The grantee listed for this patent is KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS. Invention is credited to Md. Abdul Aziz, Aasif Helal, M. Nasiruzzaman Shaikh.
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United States Patent |
10,463,391 |
Shaikh , et al. |
November 5, 2019 |
Magnetic ferrocenyl-functionalized nanoparticle
Abstract
A functionalized magnetic nanoparticle including an
organometallic sandwich compound and a magnetic metal oxide. The
functionalized magnetic nanoparticle may be reacted with a metal
precursor to form in a catalyst for various C--C bond forming
reactions. The catalyst may be recovered with ease by attracting
the catalyst with a magnet.
Inventors: |
Shaikh; M. Nasiruzzaman
(Dhahran, SA), Aziz; Md. Abdul (Dhahran,
SA), Helal; Aasif (Dhahran, SA) |
Applicant: |
Name |
City |
State |
Country |
Type |
KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS |
Dhahran |
N/A |
SA |
|
|
Assignee: |
King Fahd University of Petroleum
and Minerals (Dhahran, SA)
|
Family
ID: |
61829581 |
Appl.
No.: |
16/151,471 |
Filed: |
October 4, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190029718 A1 |
Jan 31, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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15610269 |
May 31, 2017 |
10125159 |
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62406449 |
Oct 11, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07F
17/02 (20130101); C07C 45/505 (20130101); C07C
2/861 (20130101); B01J 23/8906 (20130101); B01J
23/745 (20130101); C07C 17/269 (20130101); B01J
31/1625 (20130101); B01J 35/0013 (20130101); B01J
31/2414 (20130101); A61B 17/22 (20130101); A61B
17/320758 (20130101); C07F 15/02 (20130101); C07C
41/30 (20130101); B01J 37/0203 (20130101); B01J
37/343 (20130101); B01J 31/28 (20130101); C07C
45/50 (20130101); C07C 201/12 (20130101); B01J
35/0033 (20130101); B01J 31/2295 (20130101); C07C
45/50 (20130101); C07C 47/228 (20130101); C07C
45/505 (20130101); C07C 47/228 (20130101); C07C
45/50 (20130101); C07C 47/24 (20130101); C07C
45/505 (20130101); C07C 47/24 (20130101); C07C
45/50 (20130101); C07C 47/277 (20130101); C07C
45/505 (20130101); C07C 47/277 (20130101); C07C
2/861 (20130101); C07C 15/52 (20130101); C07C
41/30 (20130101); C07C 43/215 (20130101); C07C
17/269 (20130101); C07C 25/24 (20130101); C07C
201/12 (20130101); C07C 205/16 (20130101); C07C
201/12 (20130101); C07C 205/44 (20130101); C07C
2531/22 (20130101); B01J 2531/824 (20130101); A61B
2017/22079 (20130101); B01J 2531/842 (20130101); A61B
2017/22038 (20130101); A61B 2217/005 (20130101); B01J
2531/822 (20130101); B01J 2231/321 (20130101); A61B
2017/320775 (20130101); B01J 2540/66 (20130101); C07C
2531/28 (20130101); A61B 2017/00734 (20130101); B01J
2231/4261 (20130101) |
Current International
Class: |
A61B
17/32 (20060101); A61B 17/3207 (20060101); A61B
17/22 (20060101); A61B 17/00 (20060101) |
Foreign Patent Documents
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WO-2014164801 |
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Oct 2014 |
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WO |
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Other References
Shaikh, M.N., et al., "Magnetic Nanoparticle-Supported
Ferrocenylphosphine: a Reusable Catalyst for Hydroformylation of
Alkene and Mizoroki-Heck Olefination", RSC Advances, Issue 48, 5
Pages total (2016) (Abstract only). cited by applicant .
Kayser, B., et al., "Metal Complexes of Alkyne-Bridged
.alpha.-Amino Acids", European Journal of Inorganic Chemistry, vol.
1998, Issue 11, 3 Pages total, (Nov. 1998) (Abstract only). cited
by applicant .
Goswami, T.K., et al., "Photocytotoxic Ferrocene-Appended
(L-Tyrosine)Copper(II) Complexes of Phenanthroline Bases",
Polyhedron, vol. 52, 3 Pages total, (Mar. 22, 2013) (Abstract
only). cited by applicant.
|
Primary Examiner: Brooks; Clinton A
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a Continuation of Ser. No. 15/610,269,
now allowed, having a filing date of May 31, 2017 which claims
priority to U.S. Provisional Application No. 62/406,449 having a
filing date of Oct. 11, 2016 and which is incorporated herein by
reference in its entirety.
Claims
The invention claimed is:
1. A magnetic nanoparticle functionalized with a ferrocenyl group,
comprising: a complex represented by Formula (IIIA), Formula
(IIIB), Formula (IVA), or Formula (IVB); and an iron(III) oxide
nanoparticle; wherein the complex represented by Formula (IIIA)
Formula (IIIB), Formula (IVA), or Formula (IVB) is: ##STR00018##
where each of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is
independently a hydrogen, an optionally substituted alkyl, or an
optionally substituted aryl; each of R.sup.6 and R.sup.7 is
independently a hydrogen, an optionally substituted alkyl, an
optionally substituted aryl, an optionally substituted arylalkyl,
an optionally substituted alkoxy, or an optionally substituted
aryloxy; each of R.sup.8 is an optionally substituted alkyl, an
optionally substituted aryl, or an optionally substituted
arylalkyl; R.sup.9 is a single bond, a hydrogen, an optionally
substituted alkyl, an optionally substituted aryl, or an optionally
substituted arylalkyl; R.sup.9' is a --O--, hydrogen, an optionally
substituted alkyl, an optionally substituted aryl, an optionally
substituted arylalkyl, an optionally substituted alkoxy, an
optionally substituted aryloxy, or an optionally substituted
arylalkoxy; a and b are independently an integer in a range of
1-10; X is O or NH; M is iron; W is an optionally substituted
arylene; and wherein an oxygen atom in --OR.sup.9 group in the
complex represented by Formula (IIIA), Formula (IIIB), Formula
(IVA), or Formula (IVB) is bound to a surface of the
nanoparticle.
2. The magnetic nanoparticle of claim 1, wherein the nanoparticle
has an average diameter in a range of 1-20 nm.
3. The magnetic nanoparticle of claim 1, wherein R.sup.1 is an
optionally substituted alkyl.
4. The magnetic nanoparticle of claim 1, wherein R.sup.8 is an
optionally substituted aryl.
5. The magnetic nanoparticle of claim 1, wherein the functionalized
magnetic nanoparticle has a saturation magnetization in a range of
40-70 emu/g.
Description
STATEMENT OF FUNDING ACKNOWLEDGMENT
This project was funded by the National Plan for Science,
Technology and Innovation (MAARIFAH)-King Abdulaziz City for
Science and Technology through the Science and Technology Unit at
King Fand University of Petroleum and Minerals (KFUPM), the Kingdom
of Saudi Arabia, award number 15-NAN4650-04.
STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTORS
Aspects of this technology are described in an article "Magnetic
nanoparticle-supported ferrocenylphosphine: a reusable catalyst for
hydroformylation of alkene and Mizoroki-Heck olefination" by M.
Nasiruzzaman Shaikh, Md. Abdul Aziz, Aasif Helal, Mohamed
Bououdina, Zain H. Yamania, and Tae-Jeong Kim, in RSC Advances,
2016, pages 41687-41695, which is incorporated herein by reference
in its entirety.
BACKGROUND
Field of the Disclosure
The present disclosure relates to a functionalized magnetic
nanoparticle including an organometallic sandwich compound and a
functional group which can bind to a nanoparticle. The disclosure
also relates to a magnetic catalyst which catalyzes C--C bond
forming reactions such as hydroformylation and the Mizoroki-Heck
coupling reaction.
Description of the Related Art
Carbon-carbon bond formation reactions mediated by various
transition metals have emerged as increasingly important
methodologies for the preparation of numerous organic building
blocks for drugs, pesticides, dye, and natural products (M. A.
Gauthier, H.-A. Klok, Chem. Commun. 23 (2008) 2591-2611; D.-W. Ryu,
D. N. Primer, J. C. Tellis, G. A Molander, Chem. Eur. J. 22 (2016)
120-123; A. Brennfuhrer, H. Neumann, M. Beller, Angew. Chem. Int.
Ed. 48 (2009) 4114-4133; T. Rybak, D. G Hall, Org. Lett. 17 (2015)
4156-4159; and R. Liu, M. Zhang, T. P. Wyche, G. N.
Winston-McPherson, T. S. Bugni, W. Tang, Angew. Chem., Int. Ed. 51
(2012) 7503-7506, each incorporated herein by reference in their
entirety). Among the many frequently used C--C bond formation
protocols, such as Stille, Heck, Suzuki, Kumada, and Sonogashira,
Mizoroki-Heck for olefination and alkene hydroformylation to the
corresponding aldehyde are important in synthetic organic and
industrial chemistry (J. K. Stille, Angew. Chem. Int. Ed. 25 (1986)
508-524; R. F. Heck, Acc. Chem. Res. 12 (1979) 146-151; N. Miyaura,
A. Suzuki, Chem. Rev. 95 (1995) 2457-2483; A. Suzuki, Chem. Commun.
(2005) 4759-4763; K. Tamao, K. Sumitani, M. Kumada, J. Am. Chem.
Soc. 94 (1972) 4374-4376; T. W. Lyons, M. S. Sanford, Chem. Rev.
110 (2010) 1147-1169; S. Sobhani, Z. Pakdin-Parizi, Applied
Catalysis A: General 479 (2014) 112-120; F. Ungvary, Coord. Chem.
Rev. 251 (2007) 2087-2102, each incorporated herein by reference in
their entirety). Mizoroki-Heck reactions are often catalyzed by
different phosphine-based homogeneous Pd metal complexes. For
example, PPh.sub.3, P(o-Tol).sub.3 and P(Mes).sub.3 are used as
monodentate ligands, and dippb
(1,4-bis[(diisopropyl)phosphino]butane), dippp
(1,4-bis[(diisopropyl)phosphino]propane) and dppf
(1,1'-bis(diphenylphosphino)ferrocene) are considered bidentate
ligands (H. A. Dieck, R. F. Heck, J. Am. Chem. Soc. 96 (1974)
1133-1136; R. F. Heck, Pure & Appl. Chem. 50 (1978) 691-701; W.
A. Heinnann, C. Brobmer, K. Ofele, M. Belier, H. Fischer, J. Mol.
Catal. A: Chem. 103 (1995) 133-146; Y. Bendavid, M. Portnoy, M.
Gozin, D. Milstein, Organometallics 11 (1992) 1995-1996; M.
Portnoy, Y. Bendavid, D. Milstein, Organometallics 12 (1993)
4734-4735; and T. Jia, P. Cao, B. Wang, Y. Lou, X. Yin, M. Wang, J.
Liao, J. Am. Chem. Soc. 137 (2015) 13760-13763, each incorporated
herein by reference in their entirety). In a similar fashion, Co-,
Rh- and Ir-based metal complexes have been used for
hydroformylation in the presence of syngas and provide high
regioselectivities (C. Godard, S. B. Duckett, S. Polas, R. Tooze,
A. C. Whitwood, Dalton Trans. 14 (2009) 2496-2509; C. Kubis, M.
Sawall, A. Block, K. Neymeyr, R. Ludwig, A. Bcrner, D. Selent,
Chem. Eur. J. 20 (2014) 11921-11931; I. Piras, R. Jennerjahn, R.
Jackstell, A. Spannenberg, R. Franke, M. Beller, Angew. Chem. Int.
Ed. 50 (2011) 280-284, each incorporated herein by reference in
their entirety). However, the separation of the catalyst from the
reaction mixture by chromatography, distillation, and extraction is
highly tedious, cumbersome, and economically less viable. In
addition, the valuable metal and ligands used in the process are
not recoverable or reusable, which limits the scope of this process
for cost-effective application.
In this context, the development of environmentally benign,
reusable, and efficient organocatalysts is the central goal in
current research to contribute towards a `greener` and safe
environment. Moreover, the use of a readily available feedstock,
such as carbon monoxide, to produce more expensive functionalized
organic intermediates via hydroformylation is important. Therefore,
extensive efforts have been focused on the development of
alternatives to homogeneous catalysis to minimize separation costs
and maximize product purity. One of the options is heterogeneous
catalysis (W. Dai, Y. Zhang, Y. Tan, X. Luo, X. Tu, Applied
Catalysis A: General 514 (2016) 43-50; and R. Abu-Reziq, H. Alper,
D. Wang, M. L. Post, J. Am. Chem. Soc. 128 (2006) 5279-5282, each
incorporated herein by reference in their entirety). The method for
making heterogeneous catalysts is based on the immobilization of
ligands or metal complexes over solid supports, such as zeolites,
polymers, silica and cellulose (Z.-M. Li, Y. Zhou, D.-J. Tao, W.
Huang, X.-S. Chen, Z. Yang, RSC Adv. 4 (2014) 12160-12167; H.
Zhang, W. Yang, J. Deng, Polymer 80 (2015) 115-122; A. R. McDonald,
C. Muller, D. Vogt, G. P. M. van Klink, G. van Koten, Green Chem.
10 (2008) 424-432; and S. Zhou, M. Johnson, J. G. C. Veinot, Chem.
Commun. 46 (2010) 2411-2413, each incorporated herein by reference
in their entirety). For example, Koten et al. demonstrated the
anchoring of chiral BINAP ligands on the surface of silica, which
is highly stable, robust and easy to functionalize for the
hydrogenation reaction. Recently, Wang et al. developed a
heterocyclic carbene ligand-coated magnetic system and reported
encouraging results for the coupling reaction (Z. Wang, Y. Yu, Y.
X. Zhang, S. Z. Li, H. Qian, Z. Y. Lin, Green Chem. 17 (2015)
413-420, incorporated herein by reference in its entirety).
However, the majority of the heterogeneous catalysts exhibit lower
reactivity compared to that of their homogeneous counterpart
because the catalytic sites can be obstructed by the solid support
and become inaccessible to the substrate, decreasing the overall
catalytic activity (V. Polshettiwar, B. Baruwati, R. S. Varma,
Chem. Commun. (2009) 1837-1839; and R. S. Varma, Pure & Appl.
Chem. 85 (2013) 1703-1710, each incorporated herein by reference in
their entirety). Furthermore, solid catalyst separation processes,
such as filtration, emulsification, and centrifugation, are
complex, and can thus affect the activity and reduce the potential
reusability of conventional heterogeneous catalysts (S. Vellalath,
I. Coric, B. List, Angew. Chem. Int. Ed. 49 (2010) 9749-9752; and
M. Gemmeren, F. Lay, B. List, Aldrichim. Acta 47 (2014) 3-13, each
incorporated herein by reference in their entirety).
In view of the foregoing, an objective of the present disclosure is
to provide a heterogeneous catalyst with an activity comparable to
that of a homogenous catalyst. It is a further objective to provide
a heterogeneous catalyst which can be separated from the reaction
mixture with ease and which can be recycled with minimal loss in
catalytic activity.
SUMMARY OF THE DISCLOSURE
A first aspect of the disclosure relates to a complex represented
by Formula (IA), Formula (IB), Formula (IIA), or Formula (IIB), a
solvate, or a stereoisomer thereof, wherein Formula (IA), Formula
(IB), Formula (IIA), or Formula (IIB) are:
##STR00001##
where each of R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently a hydrogen, an optionally substituted alkyl, an
optionally substituted cycloalkyl, an optionally substituted aryl,
or an optionally substituted arylalkyl;
R.sup.5' is a hydrogen, hydroxy, cyano, nitro, an optionally
substituted alkyl, an optionally substituted cycloalkyl, an
optionally substituted aryl, an optionally substituted arylalkyl,
an optionally substituted alkoxy, an optionally substituted
cycloalkyloxy, an optionally substituted aryloxy, an optionally
substituted arylalkoxy, or an optionally substituted carbamyl;
each of R.sup.6 and R.sup.7 is independently a hydrogen, cyano,
nitro, an optionally substituted alkyl, an optionally substituted
cycloalkyl, an optionally substituted aryl, an optionally
substituted arylalkyl, an optionally substituted alkoxy, an
optionally substituted cycloalkyloxy, an optionally substituted
aryloxy, or an optionally substituted carbamyl;
each of R.sup.8 is an optionally substituted alkyl, an optionally
substituted cycloalkyl, an optionally substituted aryl, or an
optionally substituted arylalkyl;
a and b are independently an integer in a range of 1-10;
X is O or NH;
M is selected from the group consisting of chromium, nickel, iron,
lead, ruthenium, and rhodium; and
W is an optionally substituted arylene.
In one embodiment, M is iron.
In one embodiment, R.sup.1 is an optionally substituted alkyl.
In one embodiment, R.sup.8 is an optionally substituted aryl.
In one embodiment, X is NH.
In one embodiment, the complex is:
##STR00002##
A second aspect of the disclosure relates to a functionalized
magnetic nanoparticle, comprising: (i) a complex represented by
Formula (IIIA), Formula (IIIB), Formula (IVA), or Formula (IVB), a
solvate, or a stereoisomer thereof; and (ii) a nanoparticle
comprising at least one magnetic metal oxide selected from the
group consisting of nickel(II) oxide, chromium(IV) oxide,
manganese(II) oxide, manganese(III) oxide, iron(II) oxide, and
iron(III) oxide;
wherein the complex represented by Formula (IIIA), Formula (IIIB),
Formula (IVA), or Formula (IVB) is:
##STR00003##
where each of R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is
independently a hydrogen, an optionally substituted alkyl, an
optionally substituted cycloalkyl, an optionally substituted aryl,
or an optionally substituted arylalkyl;
each of R.sup.6 and R.sup.7 is independently a hydrogen, cyano,
nitro, an optionally substituted alkyl, an optionally substituted
cycloalkyl, an optionally substituted aryl, an optionally
substituted arylalkyl, an optionally substituted alkoxy, an
optionally substituted cycloalkyloxy, an optionally substituted
aryloxy, or an optionally substituted carbamyl;
each of R.sup.8 is an optionally substituted alkyl, an optionally
substituted cycloalkyl, an optionally substituted aryl, or an
optionally substituted arylalkyl;
R.sup.9 is a single bond, a hydrogen, an optionally substituted
alkyl, an optionally substituted cycloalkyl, an optionally
substituted aryl, or an optionally substituted arylalkyl;
R.sup.9' is a --O--, hydrogen, hydroxy, cyano, nitro, an optionally
substituted alkyl, an optionally substituted cycloalkyl, an
optionally substituted aryl, an optionally substituted arylalkyl,
an optionally substituted alkoxy, an optionally substituted
cycloalkyloxy, an optionally substituted aryloxy, an optionally
substituted arylalkoxy, or an optionally substituted carbamyl;
a and b are independently an integer in a range of 1-10;
X is O or NH;
M is selected from the group consisting of chromium, nickel, iron,
lead, ruthenium, and rhodium;
W is an optionally substituted arylene; and
wherein an oxygen atom in --OR.sup.9 group in the complex
represented by Formula (IIIA), Formula (IIIB), Formula (IVA), or
Formula (IVB) is bound to a surface of the nanoparticle.
In one embodiment, the nanoparticle comprises iron(II) oxide and
iron(III) oxide.
In one embodiment, the nanoparticle has an average diameter in a
range of 1-20 nm.
In one embodiment, the average diameter of the nanoparticle is in a
range of 6-8 nm.
In one embodiment, the functionalized magnetic nanoparticle has a
saturation magnetization in a range of 40-70 emu/g.
A third aspect of the disclosure relates to a catalyst, comprising
a reaction product of the functionalized magnetic nanoparticle of
the second aspect and a palladium complex or a rhodium complex,
wherein the catalyst comprises palladium or rhodium bound to a
phosphorous atom in at least one --PR.sub.2.sup.8 group.
In one embodiment, the complex is:
##STR00004##
In one embodiment, the catalyst has a saturation magnetization in a
range of 30-70 emu/g.
In one embodiment, the catalyst retains at least 90% of an initial
catalytic activity when the catalyst is reused.
A fourth aspect of the disclosure relates to a hydroformylation
method, comprising reacting an optionally substituted alkene with
carbon monoxide and hydrogen in the presence of the catalyst of the
third aspect and optionally a solvent thereby forming an aldehyde,
wherein the catalyst comprises rhodium bound to a phosphorous atom
in at least one --PR.sub.2.sup.8 group.
In one embodiment, the reacting is carried out at a pressure in a
range of 100-1,000 psi for 5-20 hours at a temperature in a range
of 40-80.degree. C., the solvent is present, and the solvent
comprises DCM, THF, or both.
In one embodiment, the method further comprises separating the
catalyst from the aldehyde, and reusing the catalyst.
A fifth aspect of the disclosure relates to a Mizoroki-Heck
coupling method, comprising reacting an optionally substituted
styrene with an aryl halide in the presence of the catalyst of the
third aspect, a solvent, and a base thereby forming a coupling
product, wherein the catalyst comprises palladium bound to a
phosphorous atom in at least one --PR.sub.2.sup.8 group.
In one embodiment, the reacting is carried out at a temperature in
a range of 50-100.degree. C. for 10 minutes to 30 hours, the
solvent comprises at least one selected from the group consisting
of DMF, water, and toluene, and the base comprises at least one
selected from the group consisting of an alkali metal hydroxide, an
alkali metal carbonate, and an amine.
In one embodiment, the method further comprises separating the
catalyst from the coupling product, and reusing the catalyst.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete appreciation of the invention and many of the
attendant advantages thereof will be readily obtained as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings, wherein:
FIG. 1A is a reaction scheme for the synthesis of
Fe.sub.3O.sub.4@dop-BPPF-Pd and Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 1B is a transmission electron micrograph of
Fe.sub.3O.sub.4.
FIG. 1C is a transmission electron micrograph of
Fe.sub.3O.sub.4@dop-BPPF.
FIG. 1D is a transmission electron micrograph of
Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 1E is a transmission electron micrograph of
Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 1F is a high resolution transmission electron micrograph of
Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 1G is a selected area electron diffraction (SAED) pattern of
Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 2 is an overlay of the XRD patterns of Fe.sub.3O.sub.4,
Fe.sub.3O.sub.4@dop-BPPF, Fe.sub.3O.sub.4@dop-BPPF-Pd, and
Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 3A is an elemental map of iron in
Fe.sub.3O.sub.4@dop-BPPF.
FIG. 3B is an elemental map of phosphorous in
Fe.sub.3O.sub.4@dop-BPPF.
FIG. 3C is an elemental map of palladium in
Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 3D is an elemental map of rhodium in
Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 4A illustrates the magnetic hysteresis loops of
Fe.sub.3O.sub.4, Fe.sub.3O.sub.4@dop-BPPF,
Fe.sub.3O.sub.4@dop-BPPF-Pd, and Fe.sub.3O.sub.4@dop-BPPF-Rh at
room temperature with a 1 tesla magnet.
FIG. 4B shows the Fe.sub.3O.sub.4@dop-BPPF-Rh particles in the vial
are attracted to the magnet placed outside the vial.
FIG. 5 is a graph illustrating the conversion of Mizoroki-Heck
reactions catalyzed by a recycled catalyst.
FIG. 6 is a reaction scheme for the synthesis of dop-BPPF.
FIG. 7 is a .sup.1H NMR spectrum of dop-BPPF in DMSO-d.sub.6.
FIG. 8 is a .sup.31P NMR spectrum of dop-BPPF in DMSO-d.sub.6.
FIG. 9 is a fast atom bombardment (FAB) mass spectrum of
dop-BPPF.
FIG. 10 is a thermogravimetry curve of Fe.sub.3O.sub.4@dop-BPPF
under argon atmosphere.
FIG. 11 is an overlay of FT-IR spectra of Fe.sub.3O.sub.4,
dop-BPPF, and Fe.sub.3O.sub.4@dop-BPPF.
FIG. 12A is an overlap of the experimental and refined XRD patterns
of Fe.sub.3O.sub.4.
FIG. 12B shows the difference between the refined and experimental
XRD patterns of Fe.sub.3O.sub.4.
FIG. 13A is an overlap of the experimental and refined XRD patterns
of Fe.sub.3O.sub.4@dop-BPPF.
FIG. 13B shows the difference between the refined and experimental
XRD patterns of Fe.sub.3O.sub.4@dop-BPPF.
FIG. 14A is an overlap of the experimental and refined XRD patterns
of Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 14B shows the difference between the refined and experimental
XRD patterns of Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 15A is an overlap of the experimental and refined XRD patterns
of Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 15B shows the difference between the refined and experimental
XRD patterns of Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 16A is an energy dispersive X-ray (EDX) spectrum of
Fe.sub.3O.sub.4@dop-BPPF-Rh.
FIG. 16B is an EDX spectrum of Fe.sub.3O.sub.4@dop-BPPF-Pd.
FIG. 17 is a gas chromatogram of the hydroformylated products of
styrene formed in DCM at 45.degree. C.
FIG. 18 is a mass spectrum of the branched aldehyde formed by
hydroformylating styrene.
FIG. 19 is a mass spectrum of the hydroformylated products of
styrene formed in THF at 45.degree. C.
FIG. 20 is a gas chromatogram of the linear aldehyde formed by
hydroformylating styrene.
FIG. 21 is a gas chromatogram of the hydroformylated products of
4-methylstyrene formed in DCM at 45.degree. C.
FIG. 22 is a mass spectrum of the branched aldehyde formed by
hydroformylating 4-methylstyrene.
FIG. 23 is a mass spectrum of the linear aldehyde formed by
hydroformylating 4-methylstyrene.
FIG. 24 is a gas chromatogram of the hydroformylated products of
4-methylstyrene formed in THF at 45.degree. C.
FIG. 25 is a gas chromatogram of the hydroformylated products of
4-vinylanisole formed in DCM at 45.degree. C.
FIG. 26 is a mass spectrum of the branched aldehyde formed by
hydroformylating 4-vinylanisole.
FIG. 27 is a mass spectrum of the linear aldehyde formed by
hydroformylating 4-vinylanisole.
FIG. 28 is a gas chromatogram of the hydroformylated products of
4-chlorostyrene formed in DCM at 45.degree. C.
FIG. 29 is a mass spectrum of the branched aldehyde formed by
hydroformylating 4-chlorostyrene.
FIG. 30 is a mass spectrum of the linear aldehyde formed by
hydroformylating 4-chlorostyrene.
FIG. 31 is a gas chromatogram of the hydroformylated products of
3-nitrostyrene formed in DCM at 45.degree. C.
FIG. 32 is a mass spectrum of the branched aldehyde formed by
hydroformylating 3-nitrostyrene.
FIG. 33 is a mass spectrum of the linear aldehyde formed by
hydroformylating 3-nitrostyrene.
FIG. 34 is a gas chromatogram of the hydroformylated products of
2-bromostyrene formed in DCM at 45.degree. C.
FIG. 35 is a mass spectrum of the branched aldehyde formed by
hydroformylating 2-bromostyrene.
FIG. 36 is a mass spectrum of the linear aldehyde formed by
hydroformylating 2-bromostyrene.
FIG. 37 is a gas chromatogram of the Mizoroki-Heck reaction product
of styrene and iodobenzene formed at 95.degree. C.
FIG. 38 is a mass spectrum of iodobenzene at Rt=7.585 minutes.
FIG. 39 is a mass spectrum of the coupling reaction product of
styrene and iodobenzene.
FIG. 40 is a gas chromatogram of the Mizoroki-Heck reaction product
of styrene and bromobenzene formed at 95.degree. C. after 1
hour.
FIG. 41 is a mass spectrum of bromobenzene at Rt=5.055 minutes.
FIG. 42 is a gas chromatogram of the Mizoroki-Heck reaction product
of styrene and bromobenzene formed at 95.degree. C. after 2
hours.
FIG. 43 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-methylstyrene and iodobenzene formed at 95.degree. C.
FIG. 44 is a mass spectrum of the Mizoroki-Heck reaction product of
4-methylstyrene.
FIG. 45 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-methylstyrene and bromobenzene formed at 95.degree. C. after
30 minutes.
FIG. 46 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-methylstyrene and bromobenzene formed at 95.degree. C. after 2
hours.
FIG. 47 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-vinylanisole and iodobenzene formed at 95.degree. C. after 30
minutes.
FIG. 48 is a mass spectrum of the Mizoroki-Heck coupling reaction
product of 4-vinylanisole.
FIG. 49 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-vinylanisole and bromobenzene formed at 95.degree. C. after 1
hour.
FIG. 50 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-chlorostyrene and iodobenzene formed at 95.degree. C. after 30
minutes.
FIG. 51 is a mass spectrum of the Mizoroki-Heck coupling reaction
product of 4-chlorostyrene.
FIG. 52 is a gas chromatogram of the Mizoroki-Heck reaction product
of 4-chlorostyrene and bromobenzene formed at 95.degree. C. after 1
hour.
FIG. 53 is a gas chromatogram of the Mizoroki-Heck reaction product
of 3-nitrostyrene and iodobenzene formed at 95.degree. C. after 30
minutes.
FIG. 54 is a mass spectrum of the Mizoroki-Heck coupling reaction
product of 3-nitrostyrene.
DETAILED DESCRIPTION OF THE DISCLOSURE
Embodiments of the present disclosure will now be described more
fully hereinafter with reference to the accompanying drawings, in
which some, but not all embodiments of the disclosure are
shown.
As used herein, the words "a", "an", and the like carry the meaning
of "one or more". Within the description of this disclosure, where
a numerical limit or range is stated, the endpoints are included
unless stated otherwise. Also, all values and subranges within a
numerical limit or range are specifically included as if explicitly
written out.
The present disclosure is further intended to include all isotopes
of atoms occurring in the present compounds. Isotopes include those
atoms having the same atomic number but different mass numbers. By
way of general example, and without limitation, isotopes of
hydrogen include deuterium and tritium. Isotopes of carbon include
.sup.13C and .sup.14C. Isotopically labeled compounds of the
disclosure can generally be prepared by conventional techniques
known to those skilled in the art or by processes and methods
analogous to those described herein, using an appropriate
isotopically labeled reagent in place of the non-labeled reagent
otherwise employed.
The first aspect of the disclosure relates to the complex
represented by Formula (IA), Formula (IB), Formula (IIA), or
Formula (IIB):
##STR00005##
Each of R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently a hydrogen, an optionally substituted alkyl, an
optionally substituted cycloalkyl, an optionally substituted aryl,
or an optionally substituted arylalkyl. In some embodiments,
R.sup.1 is an optionally substituted alkyl. Preferably, R.sup.1 is
methyl. In preferred embodiments, R.sup.2, R.sup.3, R.sup.4, and
R.sup.5 are hydrogens.
R.sup.5' is a hydrogen, hydroxy, cyano, nitro, an optionally
substituted alkyl, an optionally substituted cycloalkyl, an
optionally substituted aryl, an optionally substituted arylalkyl,
an optionally substituted alkoxy, an optionally substituted
cycloalkyloxy, an optionally substituted aryloxy, an optionally
substituted arylalkoxy, or an optionally substituted carbamyl. In
preferred embodiments, R.sup.5' is a hydroxy group.
Each of R.sup.6 and R.sup.7 is independently a hydrogen, cyano,
nitro, an optionally substituted alkyl, an optionally substituted
cycloalkyl, an optionally substituted aryl, an optionally
substituted arylalkyl, an optionally substituted alkoxy, an
optionally substituted cycloalkyloxy, an optionally substituted
aryloxy, or an optionally substituted carbamyl. Preferably, R.sup.6
and R.sup.7 are hydrogens.
Each of R.sup.8 is an optionally substituted alkyl, an optionally
substituted cycloalkyl, an optionally substituted aryl, or an
optionally substituted arylalkyl. In some embodiments, R.sup.8 is
an optionally substituted aryl. Preferably, R.sup.8 is phenyl.
The term "alkyl", as used herein, unless otherwise specified,
refers to a straight, branched, or cyclic hydrocarbon fragment.
Non-limiting examples of such hydrocarbon fragments include methyl,
ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl,
isopentyl, neopentyl, hexyl, isohexyl, 3-methylpentyl,
2,2-dimethylbutyl, 2,3-dimethylbutyl. As used herein, the term
"cyclic hydrocarbon" refers to a cyclized alkyl group. Exemplary
cyclic hydrocarbon (i.e. cycloalkyl) groups include, but are not
limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,
norbornyl, and adamantyl. Branched cycloalkyl groups, such as
exemplary 1-methylcyclopropyl and 2-methycyclopropyl groups, are
included in the definition of cycloalkyl as used in the present
disclosure.
The term "aryl", as used herein, and unless otherwise specified,
refers to a substituent that is derived from an aromatic
hydrocarbon (arene) that has had a hydrogen atom removed from a
ring carbon atom. Aryl includes phenyl, biphenyl, naphthyl,
anthracenyl, and the like.
As used herein, the term "substituted" refers to compounds where at
least one hydrogen atom is replaced with a non-hydrogen group,
provided that normal valencies are maintained and that the
substitution results in a stable compound. When a compound or a R
group (denoted as R.sup.1, R.sup.2, and so forth) is noted as
"optionally substituted", the substituents are selected from the
exemplary group including, but not limited to, alkyl; alkoxy (i.e.,
straight or branched chain optionally substituted alkoxy having 1
to 10 carbon atoms, and includes, for example, methoxy, ethoxy,
propoxy, isopropoxy, butoxy, isobutoxy, secondary butoxy, tertiary
butoxy, pentoxy, isopentoxy, hexyloxy, heptyloxy, octyloxy,
nonyloxy, and decyloxy); cycloalkyloxy (i.e., cyclopentyloxy,
cyclohexyloxy, and cycloheptyloxy); aryloxy including an optionally
substituted phenoxy; arylalkyloxy (e.g., benzyloxy); an optionally
substituted hydrocarbyl; arylalkyl; hydroxy; amino; alkylamino;
arylamino; arylalkylamino; disubstituted amines (e.g., in which the
two amino substituents are selected from the exemplary group
including, but not limited to, alkyl, aryl, or arylalkyl);
arylamino; substituted arylamino; nitro; cyano; carbamyl (e.g.
--CONH.sub.2), substituted carbamyl (e.g. --CONHalkyl, --CONHaryl,
--CONHarylalkyl or cases where there are two substituents on one
nitrogen from alkyl, aryl, or arylalkyl); aryl; substituted aryl;
and mixtures thereof and the like. The substituents may be either
unprotected, or protected as necessary, as known to those skilled
in the art, for example, as taught in Greene, et al., "Protective
Groups in Organic Synthesis", John Wiley and Sons, Second Edition,
1991, hereby incorporated by reference in its entirety).
The term "arylalkyl" as used in this disclosure refers to a
straight or branched chain alkyl moiety having 1 to 8 carbon atoms
that is substituted by an aryl group or a substituted aryl group
having 6 to 12 carbon atoms, and includes benzyl, 2-phenethyl,
2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2,4-dimethylbenzyl,
2-(4-ethylphenyl)ethyl, 3-(3-propylphenyl)propyl.
The term "hydrocarbyl" as used herein refers to a univalent
hydrocarbon group containing up to about 24 carbon atoms (i.e., a
group containing only carbon and hydrogen atoms) and that is devoid
of olefinic and acetylenic unsaturation, and includes alkyl,
cycloalkyl, alkyl-substituted cycloalkyl, cycloalkyl-substituted
cycloalkyl, cycloalkylalkyl, aryl, alkyl-substituted aryl,
cycloalkyl-substituted aryl, arylalkyl, alkyl-substituted aralkyl,
and cycloalkyl-substituted aralkyl.
The terms "a" and "b" are independently an integer in a range of
1-10, 1-8, 2-6, or 3-4. Preferably, "a" is 1 and "b" is 2. The
substituent "X" may be O or NH. Preferably, X is NH.
The substituent "W" is an optionally substituted arylene, which is
a substituent derived from an arene that has had a hydrogen atom
removed from each of two adjacent ring carbon atoms. Exemplary
arenes include an optionally substituted benzene, naphthalene,
anthracene, phenanthrene, tetracene, chrysene, triphenylene,
pyrene, pentacene, benzo[a]pyrene, corannulene, benzo[ghi]perylene,
coronene, ovalene, benzo[c]fluorene. In some embodiments, the
arylene is a phenylene.
The term "solvate" means a physical association of the complex of
this disclosure with one or more solvent molecules, whether organic
or inorganic. The physical association includes hydrogen bonding.
In certain instances the solvate will be capable of isolation, for
example when one or more solvent molecules are incorporated in the
crystal lattice of the crystalline solid. The solvent molecules in
the solvate may be present in a regular arrangement and/or a
non-ordered arrangement. The solvate may comprise either a
stoichiometric or nonstoichiometric amount of the solvent
molecules. Solvate encompasses both solution-phase and isolable
solvates. Exemplary solvates include, but are not limited to,
hydrates, ethanolates, methanolates, and isopropanolates. Methods
of solvation are generally known in the art.
The term "stereoisomer" refers to isomers that have the same
molecular formula and sequence of bonded atoms, but differ in the
three-dimensional orientations of their atoms in space.
The metal "M" is chromium, nickel, iron, lead, ruthenium, or
rhodium. Preferably, M is iron. During the past few decades,
ferrocene-based complexes have been widely studied because their
electron-rich aromatic structural motifs can be readily
functionalized by electrophilic aromatic substitution reactions. In
addition, their relatively low cost, thermal stability, high
tolerance to moisture and oxygen, and very unique chemical
properties make these materials attractive. Despite the impressive
progress in ferrocene-based homogeneous catalysis, the use of
ferrocene in heterogeneous catalysis has remained largely
unexplored.
In some embodiments, the complex is:
##STR00006##
The complex represented by Formula (IA), Formula (IB), Formula
(IIA), or Formula (IIB) may be prepared by the following procedure.
The complex precursor represented by Formula (V) or Formula (VI)
may be dissolved in a solvent (preferably an anhydrous solvent) and
then mixed with the compound of Formula (VII) or Formula (VIII) and
a base. The complex precursor is:
##STR00007## where LG is Cl, Br, I, OTf (triflate), OTs
(p-toluenesulfonate), or OAc (acetate).
The compound of Formula (VII) or Formula (VIII) is:
##STR00008##
A concentration of the precursor represented by Formula (V) or
Formula (VI) in the solvent may be in a range of 10-1,000 mM,
20-500 mM, or 40-100 mM. A concentration of the compound of Formula
(VII) or (VIII) in the resulting reaction mixture may be in a range
of 10-1,000 mM, 50-500 mM, or 100-200 mM. A concentration of the
base in the resulting reaction mixture may be in a range of 0.1-2
M, 0.3-1.5 M, or 0.5-1 M. The resulting reaction mixture may be
kept under an inert atmosphere provided by inert gases such as
argon, nitrogen, or mixtures thereof. The reaction mixture may be
agitated at a temperature of 30-95.degree. C., 50-90.degree. C., or
70-85.degree. C. for 5-30 hours, 8-20 hours, or 10-15 hours thereby
forming the complex represented by Formula (IA), Formula (IB),
Formula (IIA), or Formula (IIB). The reaction mixture may be
agitated throughout the duration of the reaction by employing a
rotary shaker, a magnetic stirrer, a centrifugal mixer, or an
overhead stirrer. In another embodiment, the reaction mixture is
left to stand (i.e. not stirred). In one embodiment, the reaction
mixture is sonicated in an ultrasonic bath or with an ultrasonic
probe. An external heat source, such as a water bath or an oil
bath, an oven, microwave, or a heating mantle, may be employed to
heat the reaction mixture. In a preferred embodiment, the external
heat source is a thermostatted thermocirculator. In some
embodiments, the reaction mixture is heated with microwave
irradiation. The complex may be isolated and purified by methods
known to those skilled in the art, such as filtration through a
celite containing cartridge, aqueous work-up, extraction with
organic solvents, distillation, crystallization, column
chromatography, and high pressure liquid chromatography (HPLC) on
normal phase or reversed phase. Preferred methods include,
evaporating the reaction mixture to dryness, purifying the residue
with column chromatography, and recrystallization. An isolated
yield of the complex may be in a range of 30-90%, 40-80%, or
50-70%.
As used herein, the term "solvent" includes, but is not limited to,
water (e.g. tap water, distilled water, doubly distilled water,
deionized water, deionized distilled water), organic solvents, such
as ethers (e.g. diethyl ether, tetrahydrofuran, 1,4-dioxane,
tetrahydropyran, t-butyl methyl ether, cyclopentyl methyl ether,
di-iso-propyl ether), glycol ethers (e.g. 1,2-dimethoxyethane,
diglyme, triglyme), alcohols (e.g. methanol, ethanol,
trifluoroethanol, n-propanol, i-propanol, n-butanol, i-butanol,
t-butanol, n-pentanol, i-pentanol, 2-methyl-2-butanol,
2-trifluoromethyl-2-propanol, 2,3-dimethyl-2-butanol, 3-pentanol,
3-methyl-3-pentanol, 2-methyl-3-pentanol, 2-methyl-2-pentanol,
2,3-dimethyl-3-pentanol, 3-ethyl-3-pentanol, 2-methyl-2-hexanol,
3-hexanol, cyclopropylmethanol, cyclopropanol, cyclobutanol,
cyclopentanol, cyclohexanol), aromatic solvents (e.g. benzene,
o-xylene, m-xylene, p-xylene, and mixtures of xylenes, toluene,
mesitylene, anisole, 1,2-dimethoxybenzene,
.alpha.,.alpha.,.alpha.,-trifluoromethylbenzene, fluorobenzene),
chlorinated solvents (e.g. chlorobenzene, dichloromethane,
1,2-dichloroethane, 1,1-dichloroethane, chloroform), ester solvents
(e.g. ethyl acetate, propyl acetate), amide solvents (e.g.
dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone), urea
solvents, ketones (e.g. acetone, butanone), acetonitrile,
propionitrile, butyronitrile, benzonitrile, dimethyl sulfoxide,
ethylene carbonate, propylene carbonate,
1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, and mixtures
thereof.
As used herein, the term "base" includes, but is not limited to, an
alkali metal hydride (e.g. sodium hydride, potassium hydride), an
alkali metal hydroxide (e.g. lithium hydroxide, potassium
hydroxide, sodium hydroxide, cesium hydroxide), an alkali metal
carbonate (e.g. lithium carbonate, potassium carbonate, sodium
carbonate, cesium carbonate), an alkali metal acetate (e.g. lithium
acetate, sodium acetate, potassium acetate), an amine (e.g.
trialkylamine of formula NR'.sub.3 (where each R' may be
independently ethyl, n-propyl, and n-butyl) and dialkylamine of
formula HNR'.sub.2, or mixtures thereof, diethylamine,
di-n-butylamine, pyrrolidine, piperidine, triethylamine,
tri-n-butylamine, diisopropylethylamine, dicyclohexylmethylamine,
pyridine, 2,6-dimethylpyridine, 4-aminopyridine,
N-methyl-2,2,6,6-tetramethylpiperidine,
2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpyridine,
1,4-diazabicyclo[2.2.2]octane), and mixtures thereof. In some
embodiments, the base is ammonium hydroxide. Preferably, the base
is triethylamine.
The second aspect of the disclosure relates to the functionalized
magnetic nanoparticle comprising (i) a nanoparticle comprising a
magnetic metal oxide, and (ii) a complex represented by Formula
(IIIA), Formula (IIIB), Formula (IVA), or Formula (IVB), a solvate,
or a stereoisomer thereof:
##STR00009##
The use of nanoparticles in catalysis is advantageous because
performance characteristics of homogeneous catalysts can be
obtained without the separation problems of homogeneous
catalysts.
The nanoparticle may preferably be spherical or substantially
spherical (e.g., oval or oblong shape). In other embodiments, the
nanoparticle can be of any shape that provides desired
photocatalytic activity. In some embodiments, the nanoparticle is
in the form of at least one shape such as a sphere, a rod, a
cylinder, a rectangle, a triangle, a pentagon, a hexagon, a prism,
a disk, a platelet, a flake, a cube, a cuboid, and an urchin (e.g.,
a globular particle possessing a spiky uneven surface).
The nanoparticles may be uniform. As used herein, the term
"uniform" refers to no more than 10%, no more than 5%, no more than
4%, no more than 3%, no more than 2%, or no more than 1% of the
distribution of the nanoparticles having a different shape. For
example, the mixed metal spheres are uniform and have no more than
1% of nanoparticles in an oblong shape. In some embodiments, the
nanoparticles may be non-uniform. As used herein, the term
"non-uniform" refers to more than 10% of the distribution of the
nanoparticles having a different shape.
Dispersity is a measure of the heterogeneity of sizes of molecules
or particles in a mixture. In probability theory and statistics,
the coefficient of variation (CV), also known as relative standard
deviation (RSD) is a standardized measure of dispersion of a
probability distribution. It is expressed as a percentage and is
defined as the ratio of the standard deviation (.sigma.) of to the
mean (.mu., or its absolute value |.mu.|). The CV or RSD is widely
used to express precision and repeatability. It shows the extent of
variability in relation to the mean of a population. The
nanoparticles having a narrow size dispersion, i.e. monodispersity,
is preferred. As used herein, "monodisperse", "monodispersed"
and/or "monodispersity" refers to nanoparticles having a CV or RSD
of less than 25%, preferably less than 20%.
The nanoparticles may be monodisperse with a coefficient of
variation or relative standard deviation (ratio of the particle
size standard deviation to the particle size mean) of less than
15%, less than 12%, less than 10%, less than 9%, less than 8%, less
than 7%, less than 6%, less than 5%, or preferably less than
2%.
In one embodiment, the nanoparticles are monodisperse and have a
particle diameter distribution in a range of 75% of the average
particle diameter to 125% of the average particle diameter,
80-120%, 85-115%, 86-114%, 87-113%, 88-112%, 89-111%, 90-110%, or
preferably 95-105% of the average particle diameter.
An average diameter (e.g., average particle diameter) of the
nanoparticle, as used herein, refers to the average linear distance
measured from one point on the nanoparticle through the center of
the nanoparticle to a point directly across from it. The
nanoparticles may have an average diameter in a range of 1-20 nm,
2-18 nm, 4-15 nm, or 6-8 nm. In some embodiments, the nanoparticles
have an average diameter in a range of 20-100 nm, 25-70 nm, or
30-40 nm. The nanoparticles may be agglomerated or, preferably,
non-agglomerated (i.e. the nanoparticles are well separated from
one another and do not form clusters). In one embodiment, the
nanoparticles are agglomerated and the agglomerates have an average
diameter in a range of 10-500 nm, 50-300 nm, or 100-200 nm. The
nanoparticles may be crystalline, polycrystalline, nanocrystalline,
or amorphous. Preferably, the nanoparticles are nanocrystalline.
The nanoparticles may have multiple phases or a single phase. A
crystallite size may range from 1-20 nm, 5-15 nm, or 8-10 nm. The
nanoparticles may have a microstrain in a range of 0.1-1%,
0.2-0.8%, or 0.3-0.5%. As used herein, the term "microstrain"
refers to the root mean square of the variations in the lattice
parameters across the individual nanocrystallites.
The nanoparticles may have a BET surface area in a range of
50-2,000 m.sup.2/g, 200-1,600 m.sup.2/g, or 500-1,400 m.sup.2/g.
The BET surface area may be determined by physical adsorption of a
gas on the surface of the nanoparticles and then calculating the
amount of adsorbate gas corresponding to a monomolecular layer on
the surface.
The dimensions and the characteristics of the nanoparticles may
vary from the described ranges and the functionalized magnetic
nanoparticle can still function as intended.
The magnetic metal oxide may be at least one metal oxide selected
from the group consisting of nickel(II) oxide, chromium(IV) oxide,
manganese(II) oxide, manganese(III) oxide, iron(II) oxide, and
iron(III) oxide. In some embodiments, the magnetic metal oxide is
manganese(II) oxide and manganese(III) oxide, or manganese(II,III)
oxide, Mn.sub.3O.sub.4. Preferably, the magnetic metal oxide is
iron(II) oxide and iron(III) oxide. In some embodiments, the
magnetic metal oxide is iron(II,III) oxide, Fe.sub.3O.sub.4. In
some embodiments, the magnetic metal oxide is ferrimagnetic
containing populations of atoms with opposing magnetic moments.
However, the opposing moments are unequal and a spontaneous
magnetization remains. In preferred embodiments, the magnetic metal
oxide shows superparamagnetism which is a form of magnetism
appearing in ferromagnetic or ferrimagnetic nanoparticles. In
sufficiently small nanoparticles, such as the nanoparticles
described herein, magnetization can randomly flip direction under
the influence of temperature. In the absence of an external
magnetic field, the magnetization appears to be zero and the
nanoparticles are in the superparamagnetic state. In this state, an
external magnetic field is able to magnetize the nanoparticles.
Superparamagnetic nanoparticles have a magnetic susceptibility
larger than that of paramagnets. The chemical and physical
properties (i.e., shape, size, and morphology) of superparamagnetic
iron oxide nanoparticles (SPION) can easily be manipulated. The
synthesis of SPION is straightforward and the nanoparticles are
easily functionalized (C. O. Dalaigh, S. A. Corr, Y. Gunko, S. J.
Connon, Angew. Chem. Int. Ed. 46 (2007) 4329-4332, incorporated
herein by reference in its entirety).
The presence of the magnetic metal oxide provides for an easy
recovery of the functionalized magnetic nanoparticle and the
catalyst of the present disclosure. For example, the functionalized
magnetic nanoparticle or catalyst is insoluble in solvents and can
be easily separated from other components of the reaction mixture
by attracting the functionalized magnetic nanoparticle or the
catalyst with a magnet.
The magnetic metal oxide may have a saturation magnetization in a
range of 5-150 emu/g, 30-100 emu/g, or 50-70 emu/g. The magnetic
susceptibilities may be measured with a laboratory magnetometer
such as a vibrating sample magnetometer, a superconducting quantum
interference device, inductive pickup coils, a pulsed field
extraction magnetometer, a torque magnetometer, a faraday force
magnetometer, and an optical magnetometer. The magnetic metal oxide
may have a coercivity (Hc) in a range of 3-4 Oe, 3.3-3.99 Oe, or
3.8-3.97 Oe. As used herein, the term "coercivity" refers to the
resistance of a magnetic material to changes in magnetization, and
is equivalent to the field intensity necessary to demagnetize the
fully magnetized material. The magnetic metal oxide may have a
remanence (Mr) in a range of 0.75-2 emu/g, 0.8-1.5 emu/g or 0.8-1
emu/g. As used here, the term "remanence" refers to the
magnetization left behind in the magnetic metal oxide after an
external magnetic field is removed. Remanence is also the measure
of that residual magnetization.
The magnetic metal oxide may be purchased or made in-house. The
magnetic metal oxide may be produced by the following procedure. A
metal salt may be mixed with an alkaline solution at 20-30.degree.
C., 22-28.degree. C., 24-26.degree. C. under an inert atmosphere.
Exemplary metal salts include, halides (e.g., fluoride, chloride,
bromide, and iodide), nitrates, acetylacetonates, acetates,
perchlorates, sulfamates, trifluoroacetylacetonates, carbonates,
bicarbonates, methanesulfonates, ethanesulfonates,
p-toluenesulfonates, salicylates, malates, maleates, succinates,
tartrates, citrates, trifluoromethanesulfonates (triflates),
hexafluorophosphates, hexafluoroacetylacetonates, sulfites,
phosphate, and sulfates of chromium, nickel, iron, lead, ruthenium,
and rhodium. In most embodiments, the metal salt is a hydrate. The
alkaline solution may have a pH in a range of 8-14, 9-13, or 10-12,
and comprises any of the aforementioned base. Preferably, the base
is ammonium hydroxide. The reaction mixture may be agitated with
the aforementioned method for 1-10, 2-8 hours, or 4-6 hours.
Preferably, the reaction mixture is stirred. The pH of the solution
may be maintained with the periodic addition (e.g., every 30-100
minutes, every 40-70 minutes, or every 50-60 minutes) of the base.
The magnetic metal oxide formed may be insoluble in the alkaline
solution and may be collected with a magnet and washed with water
several times to remove any unreacted metal salt precursors.
In some embodiments, the magnetic metal oxide is Mn.sub.3O.sub.4
and/or Fe.sub.3O.sub.4, and the magnetic metal oxide may be
prepared by mixing the respective divalent and trivalent metal
salts in a stoichiometric ratio of 1:2, or 0.8:2 to 1.2:2, 0.9:2 to
1.1:2, or 0.95:2 to 1.05:2. In some embodiments, the divalent metal
salt may be in slight excess, for example, not more than 10 mol %,
not more than 5 mol %, not more than 3 mol %, relative to the
stoichiometric amount of the trivalent metal salt. In some
embodiments, the trivalent metal salt may be in slight excess, for
example, not more than 10 mol %, not more than 5 mol %, not more
than 3 mol %, relative to the stoichiometric amount of the divalent
metal salt.
The functionalized magnetic nanoparticle may be prepared by the
following procedure. The complex of Formula (IA), Formula (IB),
Formula (IIA), or Formula (IIB) may be dissolved in the
aforementioned solvent (preferably an anhydrous organic solvent).
Preferably, the solvent is chloroform. A concentration of the
complex solution may be in a range of 1-1,000 mM, 2-500 mM, or
5-100 mM. The nanoparticles may be suspended in the same or
different solvent. Preferably, the solvent is methanol. An amount
of the nanoparticles in the suspension may be in a range of 1-500
mg/ml of solvent, 10-300 mg/ml, or 100-200 mg/ml. The complex
solution may be mixed with the suspension of the nanoparticles
under an inert atmosphere. The resulting reaction mixture may be
agitated with the aforementioned methods of agitation for 0.5-20
hours, 1-15 hours, or 5-10 hours thereby forming the functionalized
magnetic nanoparticles. In a preferred embodiment, the reaction
mixture is sonicated at a range of 20-120 kHz, 30-90 kHz, or 40-80
kHz. In some embodiments, the sonication duration is about 3-20
min, about 5-15 min, or about 8-12 min. The functionalized magnetic
nanoparticles may be collected with a magnet. The complex of
Formula (IIIA), Formula (IIIB), Formula (IVA), or Formula (IVB) may
be dispersed throughout the functionalized magnetic nanoparticle,
and may be determined by EDX spectrum and elemental maps. The
unreacted complex may be removed from the functionalized magnetic
nanoparticles by washing the functionalized magnetic nanoparticles
with the solvent.
The complex of Formula (IIIA), Formula (IIIB), Formula (IVA), or
Formula (IVB) is bound to a surface of the nanoparticle through an
oxygen atom in the --OR.sup.9 group in a monodentate or bidentate
manner via a covalent bond (e.g., non-ionic dative bond), an ionic
bond, or van der Waals force. The binding of an oxygen atom in the
--OR.sup.9 group may stabilize and minimize aggregation of the
functionalized magnetic nanoparticles (C. Duanmu, L. Wu, J. Gu, X.
Xu, L. Feng, X. Gu, Catal. Commun. 48 (2014) 45-49, incorporated
herein by reference in its entirety). In some embodiments, R.sup.9
is a single bond and/or R.sup.9' is --O--, the oxygen atom is
covalently bonded to the surface of the nanoparticle. In
alternative embodiments, the --OR.sup.9 group may be replaced with
a --NR.sub.2.sup.5 group and the functionalized magnetic
nanoparticle will still function as intended (F. Zhang, J. Jin, X.
Zhong, S. Li, J. Niu, R. Li, J. Ma, Green Chem. 13 (2011)
1238-1243; T. Jiang, S. Du, T. Jafari, W. Zhong, Y. Sun, W. Song,
Z. Luo, W. A. Hines, S. L. Suib Applied Catalysis A: General 502
(2015) 105-113; B. Baruwati, D. Guin, S. V. Manorama, Org. Lett. 9
(2007) 5377-5380; and V. Polshettiwar, R. S. Varma, Org. Biomol.
Chem. 7 (2009) 37-40, each incorporated herein by reference in
their entirety).
The functionalized magnetic nanoparticle may have a saturation
magnetization in a range of 5-150 emu/g, 30-100 emu/g, or 40-70
emu/g. The loading of the complex of Formula (IIIA), Formula
(IIIB), Formula (IVA), or Formula (IVB) on the surface of the
nanoparticle is in a range of 0.01-10 mmol/g of the nanoparticles,
0.05-1 mmol/g, or 0.2-0.5 mmol/g. The loading may be determined
from thermogravimetry.
The catalyst may be prepared by the following procedure. The
functionalized magnetic nanoparticles may be suspended in the
aforementioned solvent and agitated with the aforementioned method
for 1-120 mins, 10-100 minutes, or 20-70 minutes. Preferably, the
solvent is chloroform. An amount of the functionalized magnetic
nanoparticles in the solvent may be in a range of 1-500 mg/ml of
solvent, 10-300 mg/ml, or 50-200 mg/ml. The metal precursor may be
dissolved in the same or different solvent. Preferably, the solvent
is dichloromethane.
The metal precursor may be a binuclear metal complex, a mononuclear
metal complex, or a metal salt of ruthenium, iridium, palladium, or
rhodium. Exemplary metal precursors include, without limitation,
allylpalladium(II) chloride dimer, (2-methylallyl)palladium(II)
chloride dimer, palladium(.pi.-cinnamyl) chloride dimer,
(2-butenyl)chloropalladium dimer, palladium(II) chloride,
palladium(II) bromide, palladium(II) iodide, bis(benzonitrile)
palladium(II) chloride, bis(acetonitrile)palladium(II) chloride,
palladium(II) acetate, dichloro(mesitylene)ruthenium(II) dimer,
bis(2-methylallyl)(1,5-cyclooctadiene)ruthenium(II),
bis(1,5-cyclooctadiene)iridium(I) tetrafluoroborate,
bis(1,5-cyclooctadiene)diiridium(I) dichloride,
bicyclo[2.2.1]hepta-2,5-diene-rhodium(I) chloride dimer,
chloro(1,5-cyclooctadiene)rhodium(I) dimer,
hydroxy(cyclooctadiene)rhodium(I) dimer,
chlorobis(cyclooctene)rhodium(I) dimer,
methoxy(cyclooctadiene)rhodium(I) dimer,
chloro(1,5-hexadiene)rhodium(I) dimer,
bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate,
bis(1,5-cyclooctadiene)rhodium(I)
tetrakis[bis(3,5-trifluoromethyl)phenyl]borate,
bis(acetonitrile)(1,5-cyclooctadiene)rhodium(I)tetrafluoroborate,
bis(1,5-cyclooctadiene)rhodium(I) hexafluoroantimonate, and
bis(norbornadiene)rhodium(I) trifluoromethanesulfonate.
A concentration of the metal precursor may be in a range of
0.01-100 mM, 0.05-50 mM, or 0.1-10 mM. A molar ratio of the metal
precursor to the bound complex of Formula (IIIA), Formula (IIIB),
Formula (IVA), or Formula (IVB) may be in a range of 1:1 to 2:1,
1.1:1 to 1.9:1, or 1.3:1 to 1.5:1. The solution of the metal
precursor may then be added to the suspension of the functionalized
magnetic nanoparticles and agitated by the aforementioned method
for 0.5-10 hours, 1-8 hours, or 3-6 hours under an inert
atmosphere. The catalyst may be collected with magnet and washed
with the solvent to removed unreacted metal precursor.
The catalyst comprises palladium, rhodium, iridium, or ruthenium
bound to a phosphorous atom in at least one --PR.sub.2.sup.8 group
in the complex of Formula (IIIA), Formula (IIIB), Formula (IVA), or
Formula (IVB). The functionalized nanoparticle may bind to the
palladium, rhodium, iridium, or ruthenium in a monodentate manner
via a covalent bond (preferably a non-ionic dative bond) through a
phosphorous atom in one --PR.sub.2.sup.8 group, or in a bidentate
manner via a covalent bond (preferably a non-ionic dative bond)
through a phosphorous atom in both --PR.sub.2.sup.8 groups.
The catalyst may have a saturation magnetization in a range of
5-150 emu/g, 30-100 emu/g, 30-70 emu/g, or 30-60 emu/g. The
catalyst may have a turnover number in a range of 1,500-2,500,
preferably 1,500-2,000, more preferably 1,700-2,000 and a turnover
frequency in a range of 200-1,500 per hour, preferably 200-1,000
per hour, more preferably 200-500 per hour. Preferably, the
catalyst tolerates a variety of functional groups on the reactants.
That is, the catalyst maintains the aforementioned turnover number
and turnover frequency regardless of the functional groups on the
reactants.
The catalyst may be useful for reactions such as Mizoroki-Heck
reaction, Mizoroki-Heck-Matsuda, Sonogashira, Kumada, Negishi,
Stille, Suzuki, Hiyama, Buchwald-Hartwig, hydroformylation,
hydrogenation, allylic alkylation, Michael addition,
cyclopropanation, hydroboration, olefin isomerization and
hydroacylation, hydrosilylation and silylformylation,
cycloisomerization and cyclotrimerization, Alder-ene, allylic
substitution, carbocyclizations, carbon-hydrogen insertion,
oxidative amination, ylide rearrangements, and 1,3-dipolar
cycloadditions. Preferably, it catalyzes reactions such as a
hydroformylation reaction and a Heck reaction.
In some embodiments, the catalyst is not preformed but is formed in
situ in a reaction flask (i.e., at least one of the aforementioned
metal precursors and the functionalized magnetic nanoparticles are
added to the reaction flask separately).
In some embodiments, the catalyst comprises rhodium, ruthenium, or
iridium bound to a phosphorous atom in at least one
--PR.sub.2.sup.8 group and the catalyst catalyzes the
hydroformylation reaction. Preferably, the catalyst comprises
rhodium bound to a phosphorous atom in at least one
--PR.sub.2.sup.8 group. In a hydroformylation reaction, an
optionally substituted alkene is mixed with carbon monoxide and
hydrogen gases in the presence of the catalyst and optionally a
solvent thereby forming an aldehyde. The aldehyde may be a linear
or branched aldehyde. Prior to the mixing with carbon monoxide and
hydrogen gases, the optionally substituted alkene and the catalyst
may be mixed under an inert atmosphere in the reaction vessel and
the mixture is optionally agitated. After which, the reaction
vessel is purged with the carbon monoxide and hydrogen gases for
1-10 times, 2-8 times, or 3-6 times. A molar ratio of the carbon
monoxide gas to the hydrogen gas may be in a range of 1:3 to 3:1,
1:2 to 2:1, about 1:1. Preferably, syngas is used. The carbon
monoxide gas may be replaced by aldehydes, higher alcohols (e.g.,
cinnamyl alcohol, polyols), and metal carbonyls (e.g., Mo(CO).sub.6
and W(CO).sub.6) to reduce the use of toxic and flammable carbon
monoxide gas, and the hydroformylation may still proceed as
intended. The reacting may be carried out at a pressure in a range
of 100-2,000 psi, 200-1,500 psi, or 500-1,000 psi for 5-20 hours,
8-16 hours, or 10-14 hours at a temperature in a range of
30-90.degree. C., 40-80.degree. C., or 45-70.degree. C. under an
inert atmosphere. The reaction mixture may be optionally agitated.
The progress of each reaction may be monitored by methods known to
those skilled in the art, such as thin layer chromatography, gas
chromatography, nuclear magnetic resonance, infrared spectroscopy,
and high pressure liquid chromatography combined with ultraviolet
detection or mass spectroscopy. Preferably, gas chromatography
combined with mass spectroscopy is used.
The conversion of the optionally substituted alkene to the aldehyde
may be more than 80%, more than 90%, more than 95%, or more than
99%, based on the number of moles of the optionally substituted
alkene. The aldehyde may be linear or branched (see Table 3 for
examples of linear and branched aldehydes). In most embodiments,
the hydrogenated by-product was not observed in the reaction
mixture. For example, there may be less than 0.1 wt %, less than
0.05 wt %, or less than 0.01 wt % of the hydrogenated
by-product.
The optionally substituted alkene may be an optionally substituted
vinyl arene (e.g., styrene, 4-methyistyrene, 4-vinylanisole,
4-chlorostyrene, 3-nitrostyrene, 2-bromostyrene, and vinylbenzoate)
or n-alkene (e.g., 1-octene). An amount of the optionally
substituted alkene may be in a range of 0.1-50 mmol, 0.5-20 mmol,
or 1-10 mmol. In some embodiments, the optionally substituted
alkene may be substituted with electron-donating groups such as
amino, amido, hydroxy, alkoxyl, and alkyl. In other embodiments,
the optionally substituted alkene is substituted with
electron-withdrawing groups such as nitro, cyano, and acetyl.
Electron-withdrawing substituents are preferred because the
branched aldehydes are formed in high yields (more than 90%, more
than 95%, or more than 98%).
In some embodiments, the optionally substituted alkene is a
substituted styrene, and the aryl group may comprise up to 5
substituents. Preferably, there is one substituent. The substituent
may be located ortho, meta, or para to the vinyl group. Preferably,
the substituent is located para to the vinyl group.
The amount of catalyst may be in a range of 0.1-30 mol %, 0.5-20
mol %, or 1-10 mol %, based on the number of moles of the
optionally substituted alkene. Higher catalyst loadings (e.g. up to
20 mol %, 30 mol %, 40 mol %, 80 mol %) may be used and the method
will still proceed as intended.
In some embodiments, the solvent is present and may be DCM, THF, or
mixtures thereof. In these embodiments, a concentration of the
optionally substituted alkene is in a range of 10-1,000 mM, 50-500
mM, or 100-300 mM. The polarity of the solvent affects the
regioselectivity of the hydroformylation reaction and thus
non-polar solvents are preferably used to obtain the branched
aldehyde in high yields. A weight ratio of the branched aldehyde to
the linear aldehyde may be in a range of 200:1 to 1:200, 100:1 to
1:100, or 100:1 to 1:1. The selectivity toward the branched
aldehyde may be due to: (1) the catalytic metal binding sites being
far away from the metal nanoparticle surface and thus are not
hindered by the nanoparticles; and (2) the steric environment
around the phosphines coordinated to the catalytic metal resulted
in the predominant production of one isomer.
In some embodiments, the optionally substituted alkene is an
n-alkene, and the weight ratio of the branched aldehyde to the
linear aldehyde is in a range of 1:50 to 1:150, 1:80 to 1:120, or
1:100 to 1:110.
In some embodiments, the catalyst comprises palladium bound to a
phosphorous atom in at least one --PR.sub.2.sup.8 group and the
catalyst catalyzes the Mizoroki-Heck coupling reaction. In a
Mizoroki-Heck coupling reaction, an optionally substituted styrene
(e.g., styrene, 4-methylstyrene, 4-vinylanisole, 4-chlorostyrene,
3-nitrostyrene, 2-bromostyrene) reacts with an aryl halide in the
presence of the catalyst, the aforementioned solvent, and the
aforementioned base thereby forming a coupling product. The
reaction may be carried out at a temperature in a range of
50-100.degree. C., 60-95.degree. C., or 70-90.degree. C., for 10
minutes to 30 hours, 30 minutes to 24 hours, or 60 minutes to 4
hours. The reaction may be carried out in an inert atmosphere or in
air. The reaction mixture may be optionally agitated.
Preferably, the aryl halide is bromobenzene or iodobenzene. In
other embodiments, a benzyl halide, a vinyl halide, an aryl
triflate, a benzyl triflate, a vinyl triflate, an aryl tosylate, a
benzyl tosylate, or a vinyl tosylate may be used in place of the
aryl halide.
Exemplary halides, triflates, and tosylates include, without
limitation, 1-bromonaphthalene, 2-bromonaphthalene, bromobenzene,
4-bromoanisole, 4-bromotoluene, 1-bromo-4-fluorobenzene,
2-bromoanisole, N-methyl-2-bromopyrrole, 3-bromoindole,
5-bromo-2-methyl-1,3-benzothiazole, 3-bromobenzofuran,
3-bromobenzothiophene, 2-bromothiophene, 2-bromothiophene,
4-bromo-3-chromene, 1-bromostyrene, (E)-2-bromostyrene,
1-bromocyclohexene, 1-bromocyclopentene, bromoethene,
(E)-1-bromopropene, 2-bromopropene, iodobenzene, 1-iodonaphthalene,
2-iodonaphthalene, 4-iodoanisole, 4-iodotoluene, 4-chlorotoluene,
2-chlorotoluene, 1-chloronaphthalene, 2-chloronaphthalene,
chlorobenzene, 4-chloroanisole, 2-chloroanisole, 3-chloroindole,
N-methyl-2-chloropyrrole, 5-chloro-1,3-benzothiazole,
3-chlorobenzofuran, 3-chlorobenzothiophene, 2-chlorothiophene,
2-chlorothiophene, phenyl tosylate, allyl tosylate, 1-naphthyl
tosylate, 2-naphthyl tosylate, phenyl tosylate,
p-(ethoxycarbonyl)phenyl tosylate, p-anisyl tosylate,
p-tert-butylphenyl tosylate, o-methylphenyl tosylate, o-anisyl
tosylate, p-chlorophenyl tosylate, parabenzophenonyl tosylate,
p-formylphenyl tosylate, 2-methylcyclohexenyl tosylate,
2-methylbenzo[d]thiazol-5-yl tosylate, 1-tosyl-1H-indol-5-yl
tosylate, m-anisyl tosylate, p-(trifluoromethyl)phenyl tosylate,
and p-fluorophenyl tosylate, 1-naphthyl triflate, 2-naphthyl
triflate, phenyl triflate, p-(ethoxycarbonyl)phenyl triflate,
p-anisyl triflate, p-tert-butylphenyl triflate, o-methylphenyl
triflate, o-anisyl triflate, p-chlorophenyl triflate,
parabenzophenonyl triflate, p-formylphenyl triflate,
2-methylcyclohexenyl triflate, 2-methylbenzo[d]thiazol-5-yl
triflate, 1-tosyl-1H-indol-5-yl triflate, m-anisyl triflate,
p-(trifluoromethyl)phenyl triflate, and p-fluorophenyl triflate,
2-thienyl and 3-thienyl triflates and their benzoderivatives,
2-furanyl and 3-furanyl triflates and their benzoderivatives,
N-Boc-2-pyrrolidinyl and N-Boc-3-pyrrolidinyl triflates,
cyclohexenyl triflate, 1-styryl and (E)-2-styryl triflates. Other
traditional Heck cross-coupling partners (e.g. mesylates) and
non-traditional Heck cross-coupling partners (e.g. alkyl halides,
triflates, tosylates, etc.) are known to those of ordinary skill
and may also be suitable reaction partners in the disclosed
method.
The aryl halide comprises an optionally substituted aryl group
which may comprise the aforementioned substituents. Preferably, the
aryl group is phenyl. In a preferred embodiment, the substituents
are electron-donating groups such as amino, alkoxyl, and alkyl. In
another preferred embodiment, the substituents are
electron-withdrawing groups such as nitro, cyano, and acetyl. The
aryl group may comprise up to 5 substituents. Preferably, there is
one substituent. The substituent may be located ortho, meta, or
para to the halogen atom. Preferably, the substituent is located
para to the halogen atom.
The aryl halide may be an aryl monohalide such as aryl chloride,
aryl bromide, and aryl iodide. Preferably, the aryl monohalide is
an aryl iodide such as iodobenzene. Exemplary aryl monohalide
includes, without limitation, iodobenzene, 4-iodoaniline,
4-iodoacetophenone, 4-iodobenzonitrile, 4-iodoanisole,
bromobenzene, 4-bromoacetophenone, and 1-iodo-4-nitrobenzene. In
another embodiment, the aryl halide is an aryl dihalide such as
1,4-dichlorobenzene, 1,4-dibromobenzene, and 1,4-diiodobenzene.
The aforementioned base may be used in the Mizoroki-Heck reaction.
Preferably the base is potassium hydroxide. The presence of a base
is often important for the palladium-catalyzed Mizoroki-Heck
coupling reaction in order to neutralize the hydrogen halide
produced as the by-product of the coupling reaction (Chih-chung,
T.; Mungyuen, L.; Bingli, M.; Sarah, W.; Alan, S. C.; Chem. Lett.
2011, 40:9 955. Thorwirth, R.; Stolle, A.; Ondruschka, B.; Green
Chem. 2010, 12, 985. Bakherad, M.; Keivanloo, A.; Samangooei, S.;
Omidian, M. J. Organometal. Chem. 2013, 740, 78. Feng, Z.; Yu, S.;
Shang, Y. Appl. Organometal. Chem. 2008, 22, 577. Shingo, A.;
Motohiro, S.; Yuki, S.; Hirojiki, S.; Takuya, Y.; Aiky, O. Chem.
Lett. 2011, 40:9, 925. Korzec, M.; Bartczak, P.; Niemczyk, A.;
Szade, J.; Kapkowski, M.; Zenderowska, P.; Balin, K.; Lelarko, J.;
Polariski, J. J. Catal, 2014, 313, 1. Zhang, G.; Luan, Y.; Han, X.;
Wang, Y.; Wen, X.; Ding, C. Appl. Organometal. Chem. 2014, 28, 332,
each incorporated herein by reference in their entirety).
A concentration of the optionally substituted styrene may be in a
range of 10-1,000 mM, 50-500 mM, or 100-300 mM. A concentration of
the base in the reaction mixture may be in a range of 10-1,000 mM,
50-500 mM, or 100-300 mM. A concentration of the aryl halide in the
reaction mixture may be in a range of 5-1,000 mM, 50-500 mM, or
100-300 mM. The aryl halide may be the limiting reagent. The amount
of the optionally substituted styrene may be more than 1 molar
equivalent, more than 1.5 molar equivalents, and up to 5 molar
equivalents, up to 3 molar equivalents, or up to 2 molar
equivalents of the amount of aryl halide.
A molar ratio of the base to the optionally substituted styrene may
be in range of 10:1 to 1:10, 5:1 to 1:5, 2:1 to 1:2, or about
1:1.
The amount of catalyst may be in a range of 0.1-30 mol %, 0.5-20
mol %, or 1-10 mol %, based on the number of moles of the aryl
halide. Higher catalyst loadings (e.g. up to 20 mol %, 30 mol %, 40
mol %, 80 mol %) may be used and the method will still proceed as
intended.
The aforementioned solvent may be used in the Mizoroki-Heck
coupling reaction. Preferably, the solvent comprises at least one
selected from the group consisting of DMF, water, and toluene.
Preferably, the solvent is a mixture consisting of dimethyl
formamide and water and contains 10-50 vol %, preferably 30-50 vol
%, more preferably 40-50 vol % of water, based on a total volume of
the solvent.
In some embodiments, the solvent is water and a surfactant (e.g.,
sodium dodecylsulfate, TWEEN.RTM., and PLURONICS.TM.) may be
present to dissolve the organic reactants and facilitate their
interaction with the catalyst.
The reaction may be monitored by gas chromatography which is
optionally coupled to a mass spectrometer. The yield of the
reaction may be more than 40%, more than 60%, more than 80%, or
more than 95%. In most embodiments, the biphenyl by-product was not
observed in the reaction mixture. For example, there may be less
than 0.1 wt %, less than 0.05 wt %, or less than 0.01 wt % of the
biphenyl by-product.
The products obtained by the catalyzed methods of the present
disclosure are isolated and purified by employing the
aforementioned methods which are well-known to those skilled in the
art. The products, resulting either from a single run or a
combination of runs, comprises less than 10 ppb iron, and/or
palladium, rhodium, ruthenium, or iridium, (measured by ICP-MS),
preferably less than 5 ppb, more preferably less than 1 ppb, based
on a total weight of the product. The leaching of the catalytic
metal from the catalyst of the present disclosure into the products
is minimal and thus the catalyst may be recycled and reused without
much loss in the catalytic activity.
The reaction mixture is preferably heterogeneous and comprises
suspended catalyst particles in the liquid reaction mixture. In one
embodiment, the catalyst particles are dispersed within the
reaction mixture, and may further be filtered and recycled at the
end of the reaction. In one embodiment, the catalyst is placed in a
bag and the bag is immersed in the reaction mixture. Accordingly,
the catalyst remains in the bag until the catalyzed reaction is
completed.
In some embodiments, the method further comprises separating the
catalyst from the products, followed by recycling the used
catalyst. The catalyst may be separated by removing the bag of
catalyst, dialysis in a solvent, or using a micro-filter or a paper
filter. Preferably, the catalyst is separated from the products by
attracting the catalyst with a magnet placed at the bottom of the
exterior of the reaction vessel and then decanting the reaction
mixture.
The phrase "recycling the catalyst" refers to a process whereby the
catalyst is washed by an organic solvent, dried, and then added to
a new batch of reactants (either for the same or a different type
of catalyzed reaction). Preferred organic solvents for washing the
catalyst and/or dialysis may include, without limitation, methanol,
acetone, ethanol, tetrahydrofuran, acetonitrile, dichloromethane,
ether, glycol ether, acetamide, dimethyl acetamide, dimethyl
sulfoxide, water, or combinations thereof. The catalyst may be
dried in vacuum (e.g., in a pressure of 0.01-100 mbar, 0.1-50 mbar,
or 1-10 mbar), and/or with heating, for example, the catalyst may
be dried in a vacuum oven. Dried catalyst may be stored in a
desiccator until the next run.
In one embodiment, the catalyst is recycled for at least 2 runs,
preferably at least 10 runs, more preferably at least 20 runs, even
more preferably at least 30 runs. In some embodiments, the catalyst
may be used continuously for 10-50 days, 20-40 days, or 28-32 days.
The catalyst may lose less than 5 wt %, preferably less than 2 wt
%, more preferably less than 0.1 wt % of
palladium/rhodium/iridium/ruthenium (based on an initial amount of
palladium/rhodium/iridium/ruthenium present in the catalyst) after
the catalyst is used for several runs or several days. The yield of
the catalyzed reaction may decrease less than 20 percentage points,
less than 10 percentage points, or 5 percentage points after the
catalyst is used for several runs or several days. Preferably, the
yield of the catalyzed reaction decreases 4-8 percentage points
after the catalyst is used for 8-12 runs or 29-31 days. The
turnover number and the turnover frequency of the catalyst may
decrease less than 10%, preferably less than 5%, more preferably
less than 2% after the catalyst is used for several runs or several
days.
Having generally described this disclosure, a further understanding
can be obtained by reference to certain specific examples which are
provided herein for purposes of illustration only and are not
intended to be limiting unless otherwise specified. The examples
were published in an article "Magnetic nanoparticle-supported
ferrocenylphosphine: a reusable catalyst for hydroformylation of
alkene and Mizoroki-Heck olefination" by M. Nasiruzzaman Shaikh,
Md. Abdul Aziz, Aasif Helal, Mohamed Bououdina, Zain H. Yamania,
and Tae-Jeong Kim, in RSC Advances, 2016, pages 41687-41695, which
is incorporated herein by reference in its entirety.
EXAMPLE 1 EXPERIMENTAL MATERIALS AND METHODS
All of the chemicals were purchased from Sigma-Aldrich and used as
received unless otherwise stated. An inert atmosphere and standard
Schlenk techniques were used wherever needed. Standard procedures
were followed for preparing dry and deoxygenated solvents.
Deionized (DI) water was used throughout the experiments. The
surface coating was carried out in a low-power bath sonicator
(Cole-Parmer model 08892-21). The .sup.1H and .sup.13C NMR spectra
were recorded on a JEOL JNM-LA 500 spectrometer with
tetramethylsilane (TMS) as the internal standard. The .sup.31P NMR
spectra were recorded on the same spectrometer using a phosphorous
probe and 85% H.sub.3PO.sub.4 as the internal reference. The FTIR
spectra were obtained on a Nicolet 720 in the range of 400 to 4000
cm.sup.-1 using KBr pellet. The thermogravimetric analysis (TGA)
data were obtained on a Mettler-Toledo model TGA1 STAR.sup.e System
at a heating rate of 10.degree. C./min in a temperature range of
25-600.degree. C. in an argon atmosphere. The X-ray diffraction
data were collected on a Rigaku model Ultima-IV diffractometer
using Cu-K.alpha. radiation. The nanoparticles were imaged by field
emission scanning electron microscopy (FESEM) on a LYRA 3 Dual Beam
Tescan operated at 30 kV. The SEM samples were prepared from
ethanolic suspensions on alumina stabs and coated with gold in an
automatic gold coater (Quorum, Q150T E). For the elemental analysis
and mapping, the energy dispersive X-ray spectra (EDS) were
collected on the LYRA 3 Dual Beam Tescan. The transmission electron
micrographs were collected on a transmission electron microscope
(TEM) (JEOL, JEM 2011) operated at 200 kV with a 4 k.times.4 k CCD
camera (Ultra Scan 400SP, Gatan). The TEM samples were prepared by
dropwise application of an ethanolic suspension onto a copper grid
and the sample was allowed to dry at room temperature. The
catalytic reactions were performed in a STEM Omni.RTM. 10-place
reaction station and a Teflon-lined autoclave from HiTech, USA
(model: M010SSG0010-E129A-00022-1D1101), which was equipped with a
pressure gauge and mechanical stirrer. The magnetic
susceptibilities were measured using a vibrating sample
magnetometer (VSM, model PMC Micromag 3900) equipped with a 1 tesla
magnet at room temperature.
EXAMPLE 2 SYNTHESES OF THE COMPOUNDS, COMPLEX, FUNCTIONALIZED
MAGNETIC NANOPARTICLE, AND CATALYST
The syntheses of N,N-dimethylferrocenyl ethyl amine (FA),
N,N-dimethyl-1-[-1',2-bis(diphenylphosphino)ferrocenyl]ethyl amine
(BPPFA) and 1-[-1',2-bis(diphenylphosphino)ferrocenyl]ethyl acetate
(BPPFA-OAc) were performed according to previously reported
procedures (G.-H. Hwang, E.-S. Ryu, D.-K. Park, S. C. Shim, C. S.
Cho, T.-J. Kim, J. H. Jeong, M. Cheong, Organometallics 20 (2001)
5784-5787; and T. Hayashi, T. Mise, M. Fukushima, M. Kagotani, N.
Nagashima, Y. Hamada, A. Matsumoto, S. Kawakami, M. Konishi, Bull.
Chem. Soc. Japan 53 (1980) 1138-1151, each incorporated herein by
reference in their entirety).
The synthesis involved the preparation of
N,N-dimethyl-1-ferrocenylethylamine followed by dilithiation and
reaction with chlorodiphenylphosphine to afford BPPFA (see FIG. 6)
(T. Hayashi, K. Yamamoto, M. Kumada, Tetrahedron Lett. (1974)
4405-4408, incorporated herein by reference in its entirety). The
freshly prepared BPPFA was acetylated to replace the --NMe.sub.2
functional group by reaction with acetic anhydride at 100.degree.
C. for 1 hour to yield BPPFA-OAc.
The synthesis of a new ferrocene-based ligand (dop-BPPF,
{.eta..sup.5-C.sub.5H.sub.4--PPh.sub.2}Fe{.eta..sup.5-C.sub.5H.sub.3-1-PP-
h.sub.2-2-CH(Me)NH--CH.sub.2--CH.sub.2-4-C.sub.6H.sub.3-1,2-OH})
from BPPFA-OAc (1-[1',2-bis(diphenylphosphino)-ferrocenyl]ethyl
acetate) is described hereinafter (M. N. Shaikh, M. Bououdina, A.
A. Jimoh, M. A. Aziz, A. Helal, A. S. Hakeem, Z. H. Yamani, T.-J.
Kim, New J. Chem. 39 (2015) 7293-7299; M. N. Shaikh., V. D. M.
Hoang, T-J. Kim, Bull. Korean Chem. Soc. 30 (2009) 3075-3078; and
H.-K. Kim, J.-A. Park, K. M. Kim, M. N. Shaikh, D.-S. Kang, J. Lee,
Y. Chang, T.-J. Kim, Chem. Commun. 46 (2010) 8442-8444, each
incorporated herein by reference in their entirety).
Ferrocenylphosphine was used because the phosphine group can
coordinate to the catalytic metal (i.e., rhodium or palladium) and
the resulting catalyst was found to be stable with excellent
catalytic activity. FIG. 1 shows the preparation route for the
formation of dopamine-functionalized ferrocenylphosphine.
Synthesis of
{.eta..sup.5-C.sub.5H.sub.4--PPh.sub.2}Fe{.eta..sup.5-C.sub.5H.sub.3-1-PP-
h.sub.2-2-CH(Me)NH--CH.sub.2--CH.sub.2-4-Ph-1,2-OH} (dop-BPPF): To
a solution of BPPFA-OAc (0.28 g, 0.43 mmol) in anhydrous methanol
(10 mL), dopamine hydrochloride (0.19 g, 1.0 mmol) and freshly
distilled triethylamine (1 mL) were added under an argon atmosphere
(dopamine hydrochloride was made soluble in anhydrous methanol by
the excess trimethylamine). The mixture was stirred at 85.degree.
C. for 12 hours, and then the solvent was removed under vacuum. The
solid residue was dissolved in a minimal amount of methanol and
transferred to a silica gel column for separation. The desired
orange band was eluted using a combination of ethyl acetate and
methanol (9:1) to produce orange solids after removal of the
solvents. Recrystallization from methanol/cyclohexane yielded 0.18
g of product (56%). .sup.31P NMR (202 MHz, in DMSO-d.sub.6):
.delta. -28.14 (s, PPh.sub.2), -20.78 (s, PPh.sub.2). .sup.1H NMR
(DMSO-d.sub.6): .delta. 1.30 (d, J=6.7, 3H, CHCH.sub.3), 1.78 (t,
2H, NCH.sub.2CH.sub.2), 2.29 (t, 2H, NCH.sub.2CH.sub.2), 3.55 (m,
3H, C.sub.5H.sub.3), 4.04-4.49 (m, 4H, C.sub.5H.sub.4), 6.20 (d,
1H, C.sub.6H.sub.3), 6.39 (s, 1H, C.sub.6H.sub.3), 6.60 (d, 1H,
C.sub.6H.sub.3), 7.24-7.50 (m, 20H, PPh.sub.2), 8.62 (s, 1H, OH),
8.74 (s, 1H, OH). .sup.13C NMR (DMSO-d.sub.6): 19.03 (CHCH.sub.3),
35.12 (NCH.sub.2CH.sub.2), 69.37 (NCH.sub.2CH.sub.2), 72.81
(CHCH.sub.3), 115.29, 118.91, 128.20, 129.23, 132.11
(C.sub.6H.sub.3), 132.67, 132.82, 133.04, 134.43, 143.20, 144.81
(C.sub.5H.sub.3, C.sub.5H.sub.4 and PPh.sub.2). FTIR in KBr
(cm.sup.-1): v=3426 (O--H), 3058 (arC--H), 2920 (Csp.sup.3-H)
1522(arC--C). FAB-MS(m/z): calc. for
C.sub.44H.sub.41FeNO.sub.2P.sub.2, 733.198([M].sup.+); found,
733.196. Anal. Calcd for
C.sub.44H.sub.41FeNO.sub.2P.sub.2.CH.sub.3OH: C, 70.59; H, 5.92; N,
1.83. Found: C, 70.67; H, 6.17; N, 2.01.
Characteristic singlets appeared in the highly shielded (upfield)
region (-20 and -28 ppm) in the .sup.31P NMR spectra and were
assigned to the phosphorous atom in the diphenylphosphine groups
attached to the ferrocene ring (see FIG. 8). The presence of
ferrocenyl ring protons in the 3.5-4.5 ppm region, an axial methyl
proton chemical shift (.delta.) at 1.30 ppm, and three protons of
the phenyl ring of dopamine at 6.20, 6.39 and 6.60 ppm confirmed
the formation of the desired compound (see FIG. 7). This compound
was further characterized by FAB-mass spectrometry and exhibited
the characteristic molecular ion peak (m/z=733.196) (see FIG.
9).
Synthesis of Fe.sub.3O.sub.4: Magnetite nanoparticles of 6-8 nm in
size were prepared by reaction of divalent and trivalent iron in a
1:2 ratio in an alkaline medium at room temperature under an argon
atmosphere with constant stirring (500 rpm). The pH of the solution
was held constant with the periodic addition of conc. NH.sub.4OH
for 4 hours. A black precipitate was collected using a magnet and
washed with DI water several times to remove any unreacted iron
precursors.
Synthesis of
Fe.sub.3O.sub.4@{.eta..sup.5-C.sub.5H.sub.4--PPh.sub.2}Fe{.eta..sup.5-C.s-
ub.5H.sub.3-1-PPh.sub.2-2-CH(Me)NH--CH.sub.2--CH.sub.2-4-Ph-1,2-OH}
(Fe.sub.3O.sub.4@dop-BPPF): The magnetite nanoparticles (MNPs) were
functionalized (see FIG. 1) using a previously reported procedure
modified as follows: To a suspension of magnetic nanoparticles (200
mg) in anhydrous chloroform, dop-BPPF (200 mg) solution in dry
methanol was added under an argon atmosphere. The mixture was
sonicated in a bath sonicator for 6 hours. The surface
functionalized magnetic nanoparticles were collected using a magnet
after repeated washing with methanol followed by characterization.
FTIR in KBr (cm.sup.-1): v=3435 (O--H+N--H), 2938 (arC--H), 1428
(arC--C), 590 (Fe--O).
Ferrocenylphosphine was linked to the dopamine moiety, which was
used as an anchoring unit to attach the complex onto the surface of
the magnetic nanoparticles. Bidentate enediol ligands provide
higher stability and tight binding to iron oxide by transforming
under-coordinated Fe surface sites back to a bulk-like octahedral
lattice structure for oxygen-coordinated magnetite, and this
behavior is further supported by the Langmuir isotherm, which
indicated that the adsorption of dopamine moiety via the
1,2-dihydroxyl functional group was more favorable than its
desorption from the metal nanoparticles surface (G. W. Gokel, I. K.
Ugi, J. Chem. Educ. Chem. 49 (1972) 294-296; and L. X. Chen, T.
Liu, M. C. Thurnauer, R. Csencsits, T. Rajh, J. Phys. Chem. B 106
(2002) 8539-8546, each incorporated herein by reference in their
entirety).
Synthesis of
Fe.sub.3O.sub.4@{.eta..sup.5-C.sub.5H.sub.4--PPh.sub.2}Fe{.eta..sup.5-C.s-
ub.5H.sub.3-1-PPh.sub.2-2-CH(Me)NH--CH.sub.2--CH.sub.2-4-Ph-1,2-OH}-M
(Fe.sub.3O.sub.4@dop-BPPF-M): The suspension of the magnetite
nanoparticles (100 mg) in chloroform was sonicated for 1 hour. The
solution of [Rh(NBD)Cl].sub.2 (0.015 mmol), slightly excess, in
dichloromethane was added to the suspension and stirred for 4 hours
under argon atmosphere. The materials was collected and washed with
dichloromethane to remove unreacted metal precursor.
The same procedure was followed to prepare
Fe.sub.3O.sub.4@dop-BPPF-Pd and [Rh(NBD)Cl].sub.2 was replaced with
[Pd(C.sub.3H.sub.5)Cl].sub.2.
EXAMPLE 3 CHARACTERIZATION OF THE SYNTHESIZED COMPLEX,
FUNCTIONALIZED MAGNETIC NANOPARTICLE, AND CATALYST
FIGS. 1B, 1C, 1D, and 1E are the transmission electron micrographs
of Fe.sub.3O.sub.4, Fe.sub.3O.sub.4@dop-BPPF,
Fe.sub.3O.sub.4@dop-BPPF-Pd, and Fe.sub.3O.sub.4@dop-BPPF-Rh,
respectively. The micrographs show that the nanoparticles are
spherically-shaped and uniformly distributed. The average diameter
was 6-8 nm. The high-resolution transmission electron micrograph
and selected area electron diffraction (SAED) image are shown in
FIGS. 1F and 1G, respectively. The interplanar distance was
determined to be consistent with the literature data (T. Rajh, L.
X. Chen, K. Lukas, T. Liu, M. C. Thurnauer, D. M. Tiede, J. Phys.
Chem. B 106 (2002) 10543-10552, incorporated herein by reference in
its entirety). The SAED data also revealed higher order
crystallinity, which was further confirmed by the X-ray diffraction
(XRD) signature of the nanomaterial. The peaks located at
30.22.degree., 35.70.degree., 43.10.degree., 53.40.degree.,
57.10.degree. and 63.20.degree. indicate the formation of a
nanocrystalline cubic (Fd3m) spinel Fe.sub.3O.sub.4 nanostructure
(JCPDS card No. 01-075-0449) (N. Pinna, S. Grancharov, P. Beato, P.
Bonville, M. Antonietti, M. Niederberger, Chem. Mater. 17 (2005)
3044-3049, incorporated herein by reference in its entirety).
Therefore, coating the nanoparticles with dop-BPPF followed by
complexation with Pd/Rh did not alter the original crystal
structure of the parent compound (Fe.sub.3O.sub.4). Qualitative and
quantitative phase analyses were carried out using the Rietveld
method. The XRD patterns were refined by the Rietveld method (see
FIGS. 12A, 12B, 13A, 13B, 14A, 14B, 15A, and 15B) and confirmed the
formation of a single phase (the goodness fit factor was close to
1) (see Table 1). The calculated crystallite size was determined to
be approximately 8.5 nm for all of the samples, which was in good
agreement with the size obtained from TEM analysis. The calculated
lattice parameter was approximately 8.36 .ANG., which was close to
that of bulk magnetite. Elemental maps, as shown in FIGS. 3A-3D,
indicate the uniform anchoring of the ferrocenylphosphine ligands
and the complexed ligand with Rh and Pd on the surface of the
nanoparticles. The presence of these elements was confirmed by the
EDS results (see FIGS. 16A and 16B).
The Fourier transform infrared (FTIR) spectroscopic data revealed a
vibration red shift of Fe-O by 7 nm from 583 nm for the parent
magnetite with a bare surface. The characteristic aromatic C--H
stretching at 2938 cm.sup.-1 and aromatic C--C at 1428 cm.sup.-1
confirmed the presence of dop-BPPF on the surface.
The thermal stability of dop-BPPF was investigated, and the
stepwise weight loss profile was determined under an argon
atmosphere in a temperature range of 25-600.degree. C. (see FIG.
10). The amount of weight loss was determined to be approximately
14%, which indicated that the amount of loading on the nanoparticle
surface was 0.2 mmol of dop-BPPF per gram of magnetic
nanoparticles. These data were further confirmed by the amount of
phosphine determined from the EDS results.
The recorded magnetic data revealed the superparamagnetic nature of
all of the samples at room temperature (see FIG. 4A). Prior to
coating, the magnetization of the bare surface of the magnetite
(Fe.sub.3O.sub.4) was 67 emu g.sup.-1, and the magnetization the
surface-coated nanoparticles (Fe.sub.3O.sub.4@dop-BPPF) was 58 emu
g.sup.-1. The saturation magnetization value slightly decreased due
to the coating with dop-BPPF and complexation with Pd and Rh. It is
important to note that the coercivity (Hc) and remanence (Mr) were
not affected by the surface functionalization and complexation
processes. The coating of dop-BPPF and presence of Pd/Rh did not
substantially affect the bulk magnetization, which is very
important for the separation process, and these data were further
confirmed by the physical use of a magnet near to the vial
containing the particles (see FIG. 4B).
TABLE-US-00001 TABLE 1 Structural, microstructural of magnetite
Fe.sub.3O.sub.4 before and after coating and complexation with Pd
and Rh. Crystallite Lattice Goodness size Microstrain parameter of
(nm) (%) (.ANG.) fit Fe.sub.3O.sub.4 8.4 0.360 8.372(4) 1.0726
Fe.sub.3O.sub.4@dop-BPPF 8.5 0.478 8.365(4) 1.1276
Fe.sub.3O.sub.4@dop-BPPF-Pd 8.6 0.500 8.363(4) 1.1079
Fe.sub.3O.sub.4@dop-BPPF-Rh 8.4 0.340 8.359(4) 1.1300
TABLE-US-00002 TABLE 2 Magnetic properties investigation data of
magnetite Fe.sub.3O.sub.4 before and after coating and complexation
with Pd and Rh. Coercivity, Saturation H.sub.c Remanence, M.sub.r
magnetization, M.sub.s (Oe) (emu/g) (emu/g) Fe.sub.3O.sub.4 3.965
0.802 68.03 Fe.sub.3O.sub.4@dop-BPPF 4.322 0.645 58.75
Fe.sub.3O.sub.4@dop-BPPF-Rh 4.480 0708 56.00
Fe.sub.3O.sub.4@dop-BPPF-Pd 4.614 0.722 54.15
EXAMPLE 4 PROCEDURE FOR THE HYDROFORMYLATION REACTION
This reaction was carried out in a functional fume hood fitted with
good suction. The functionalized magnetic nanoparticles,
Fe.sub.3O.sub.4@dop-BPPF-Rh (50 mg), styrene (1.0 mmol, 0.12 mL)
and freshly distilled THF (10 mL) were added to a Teflon-lined
autoclave equipped with a pressure gauge and a mechanical stirrer
under an argon atmosphere. Next, the inert atmosphere was replaced
with a mild pressure release of CO/H.sub.2 gas for three cycles.
Then, the autoclave was pressurized with CO/H.sub.2 (1:1) at 1000
psi, and the temperature was maintained at 45.degree. C. After
completion of the reaction, the pressure was released, and the
sample was passed through a short silica gel column followed by
injection into a gas chromatograph to determine the conversion and
regioselectivity values.
The catalytic activity was evaluated using various substituted
styrenes and n-alkenes at 45.degree. C. with a mixture of carbon
monoxide and hydrogen (1:1) under a pressure of 1000 psi. The
results are shown in Table 3. A study on the reaction conditions
was performed using styrene as a model substrate. At 45.degree. C.,
85% conversion of styrene to the corresponding aldehyde was
achieved with a branched (B) to linear (L) ratio of 8:1 at 200 psi
(entry #1). As the reaction temperature increased to 70.degree. C.,
the yield improved but the regioselectivity was lost (entry #2).
The solvent polarity played an important role in the selectivity.
Based on the results in Table 1, a more polar solvent negatively
affected the selectivity. Among all of the tested solvents,
dichloromethane was the most efficient solvent for this reaction.
For example, although a high selectivity (B:L=17:1) was obtained by
employing a pressure of 1000 psi in THF at 45.degree. C., a
substantial improvement was observed when the same reaction was
performed in dichloromethane, and the regioselectivity increased to
28:1 from 17:1 (entries #3 and 4) and to 52:1 from 14:1 (entries #6
and 7) for styrene and 4-methylstyrene, respectively.
Styrene substituted with different electron-withdrawing and
-donating groups were used as substrates for the hydroformylation
reaction. Although no noticeable change in the reactivity was
observed, a profound effect was observed for the selectivity. The
selectivity ratio for the branched to linear isomers of
nitrostyrene and bromostyrene was 99:1 (entries #10 and 11). The
hydroformylation of styrene under solvent-free conditions resulted
in 86% conversion (entry #5) with 85% branched isomer. Thus, this
system can be employed as a green catalyst in the hydroformylation
reaction without the use of any organic solvents. For n-alkene, the
reactivity of the catalyst was slow. The conversion of 1-octene
(entry #14) reached 85% but the linear aldehyde was formed
(B:L=0:100). This result was consistent with previously reported
data. Also, no hydrogenated product was observed in the
Rh-catalyzed hydroformylation.
The recyclability of the catalysts was investigated by employing
the reaction conditions described herein. After the first round of
catalysis, the nanocatalysts were washed with dichloromethane to
remove any unwanted materials and reused for the 2.sup.nd round of
catalysis without the addition of more Rh metal precursor. A
gradual loss in the catalytic activity was observed after the
4.sup.th run, which may be due to the high pressure being employed
in the reaction system, and the active catalyst was leached from
the surface of the magnetic nanoparticles.
TABLE-US-00003 TABLE 3 Hydroformylation.sup.a of olefins using
Fe.sub.3O.sub.4@dop-BPPF and [Rh(NBD)Cl].sub.2 metal precursor.
##STR00010## ##STR00011## Time Pressure Temp Conv..sup.b Branch.
Linear Ratio Entry Substrate (h) (psi) Solvent (.degree. C.) (%)
(B) (L) (B:L) 1 Styrene 9 200 THF 45 85 88.6 11.4 8 2 Styrene 10
200 THF 70 91 48.1 51.9 0.9 3 Styrene 8 1000 THF 45 >99 94.5 5.5
17 4 Styrene 8 1000 DCM 45 >99 96.4 3.6 28 5 Styrene 14 1000 No
solv. 45 86 85.4 14.6 6 6 4- 14 1000 THF 45 >99 93.4 6.6 14
Methylstyrene 7 4- 14 1000 DCM 45 >99 98.1 1.9 52 Methylstyrene
8 4-Vinylanisole 14 1000 DCM 45 >99 97.2 2.8 35 9 4-Chlorosyrene
12 1000 DCM 45 >99 98.6 1.4 70 10 3-Nitrostyrene 13 1000 DCM 45
>99 99 1 99 11 2- 13 1000 DCM 45 >99 99 1 99 Bromostyrene 12
Vinylbenzoate 16 1000 DCM 45 96 13 1-Octene 16 1000 DCM 45 85 --
100 -100 .sup.a1 mmol of styrene in 10 mL anhydrous solvent under
syn gas (CO:H.sub.2 1:1) pressure using 50 mg of
Fe.sub.3O.sub.4@dop-BPPF-Rh and Rh-metal precursor .sup.bdetermined
by GC and identified by GC-MS; nd: not determined
EXAMPLE 5 PROCEDURE FOR THE MIZOROKI-HECK REACTION
This reaction was performed in a reaction tube fitted with a
magnetic stirrer and a Teflon stopper, and the reaction tube was in
a parallel reactor. To a suspension of the catalyst,
Fe.sub.3O.sub.4@dop-BPPF-Pd (50 mg), in DMF:water (1:1) (10 mL),
styrene (1.0 mmol, 0.12 mL) and potassium hydroxide (1.0 mmol, 56
mg) were added. The temperature was maintained at 90.degree. C. The
progress of the reaction was monitored by a gas chromatograph,
which was connected to a mass detector, and the product was
extracted using ethyl acetate. The concentrated solution was passed
through a short silica gel column and eluted with hexane:ethyl
acetate (9:1).
In a study of the reaction conditions of the Mizoroki-Heck
reaction, styrene and iodobenzene were chosen as the model
substrates to evaluate the catalytic activity. The results are
shown in Table 4. The effect of the temperature was investigated. A
higher temperature was determined to be effective, which was
confirmed by the results in entries #1 and 2. At 95.degree. C.,
styrene was quantitatively converted to its corresponding product.
However, at a lower temperature, the conversion was 50% (entry #1).
In this reaction, the base played a crucial role in the
regeneration of Pd active species. Therefore, K.sub.2CO.sub.3,
Et.sub.3N and KOH were used in the DMF:H.sub.2O (1:1) solvent
mixture, and the highest conversion was obtained using KOH (entry
#2) compared to that using potassium carbonate or triethylamine
(entries #3 and 4). The solvent effect was investigated by
employing a series of solvent systems, such as water, toluene, DMF,
and DMF:water (1:1). The catalytic yield in pure water was only 67%
(entry #5), which may be due to the insolubility of organic
substrate in water and thus the substrate was not able to contact
the metal reaction sites effectively. However, the DMF:water (1:1)
mixture was a better solvent compared to that of pure DMF (entries
#2 and 7).
TABLE-US-00004 TABLE 4 A study of the reaction conditions of the
Mizoroki-Heck reaction between iodobenzene and styrene.
##STR00012## ##STR00013## ##STR00014## Temp Conversion.sup.a Entry
Base (.degree. C.) Solvent (%) 1 KOH 60 DMF-H.sub.2O (1:1) 50 2 KOH
95 DMF-H.sub.2O (1:1) 99 3 K.sub.2CO.sub.3 95 DMF-H.sub.2O (1:1) 69
4 Et.sub.3N 95 DMF-H.sub.2O (1:1) 56 5 KOH 95 H.sub.2O 67 6 KOH 95
Toluene 44 7 KOH 95 DMF 81 .sup.aConversion measured after 30
minutes of reaction Yields are based on iodobenzene;
.sup.bdetermined by GC and identified by GC-MS
Using the reaction conditions described above, the coupling
reaction was extended to a range of substituted styrene substrates
to explore the scope of the newly developed catalytic system, and
the results are summarized in Table 5. Bromobenzene was much less
reactive with styrene than the corresponding iodobenzene (entries
#1 and 2). However, prolonging the reaction time to 2-24 hours
resulted in quantitative conversion. This result indicated the
catalyst was stable for the extended reaction time. The
electron-withdrawing group in the para and meta positions of
styrene (entries #7-10) decreased the reaction rate. For example,
using 4-chlorostyrene (entries #7 and 8), the maximum conversion
was 69% after 24 hours, and the same trend was observed for
3-nitrostyrene (entry #10), which yielded 85% of the coupling
product. Also, no biphenyl product was observed in the Pd-catalyzed
Mizoroki-Heck reaction.
The reusability of the nanocatalysts was investigated using the
reaction of styrene and iodobenzene at 95.degree. C., in a
DMF:water 1:1 solvent mixture, and KOH base. The results are shown
in FIG. 5 as a bar chart. After completion of the coupling
reaction, the catalyst was collected by placing an external magnet
at the bottom of the reaction vessel, and the solution was decanted
for work up and gas chromatography. The collected catalyst
particles were repeatedly washed with ethyl acetate and water prior
to use in the next round of catalysis. The catalyst exhibited a
consistent activity up to the 10.sup.th consecutive cycle after the
reaction time was increased to 12 hours. Intrigued by its
robustness, the collected catalysts from the 10.sup.th cycle were
placed in the same coupling reaction for 30 days, and surprisingly,
the observed loss of activity remained almost the same.
TABLE-US-00005 TABLE 5 A study of the reaction conditions for the
Mizoroki-Heck reaction.sup.a between aryl halide and substituted
styrene. ##STR00015## ##STR00016## ##STR00017## Substrate Halide
Time Entry (R) (X) (min) Conversion.sup.b 1 H I 30 99 2 H Br 30 78
60 80 120 96 24 h 99 3 4-CH.sub.3 I 30 96 4 4-CH.sub.3 Br 30 87 60
95 120 98 5 4-OCH.sub.3 I 30 99 6 4-OCH.sub.3 Br 30 77 60 94 120 96
7 4-Cl I 30 98 8 4-Cl Br 30 35 60 60 120 66 24 h 69 9 3-NO.sub.2 I
30 94 60 97 10 3-NO.sub.2 Br 30 22 60 27 24 h 85 11 2-Br I 30 96
.sup.areactions were carried out at 95.degree. C. in DMF:H.sub.2O
(1:1) using KOH as base and Fe.sub.3O.sub.4@dop-BPPF-Pd; yields are
based on halobenzene; .sup.bdetermined by GC and identified by
GC-MS
* * * * *